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| Kristen Eller ©2002 |
The number of elementary 2-fold polychords. [Keith]
The smallest prime whose reversal is a power: 32 = 25. [Trigg]
23 is the smallest prime for which the sum of the squares of its digits is also an odd prime. [Trotter]
The floor function of e = 23.
23 is formed from the concatenation of the first two primes.
The suicidal bomber has seat number 23 in the film Airport (1970).
The smallest prime number that is not the sum of two Ulam numbers. The (standard) Ulam numbers start with 1 and 2; then the subsequent terms are the smallest numbers that can be expressed in just one way as the sum of two distinct earlier terms. The sequence begins 1, 2, 3, 4, 6, 8, 11, 13, .... [Guy]
230 + 231 + 232 + 233 + 235 = 6449063 and the sum of 6 + 4 + 4 + 9 + 0 + 6 + 3 can be
written as 3 * 2 + 2 * 2 + 2 * 2 + 3 * 3 + 0 + 3 * 2 + 3 = 32, the reversal of 23. [Gevisier]
23 is the only prime number p such that p! is p digits long. [Gupta]
The smallest isolated prime, i.e., not an element of a set of twin primes. [Francis]
"Hilbert's problems" are a list of 23 problems put forth by David Hilbert in the year 1900. Note the number of words in the following quote attributed to him: "If I were to awaken after having slept for a thousand years, my first question would be: has the Riemann hypothesis been proven?" [Beedassy]
The "23 Enigma" is a belief that the number 23 is of particular or unusual significance.
Every positive integer is the sum of at most nine cubes. Only 23 and 239 require all nine! Waring's problem (1770) asks: if given k, is there some number g(k) for which every positive integer can be written as the sum g(k) (or fewer) kth powers? For example, g(3) = 9 and g(4) = 19. In 1909, Hilbert proved the answer was yes.
Psi (y) is the 23rd letter of the Greek alphabet. [Roberts]
Homo sapiens have 23 pairs of chromosomes.
(35 + 53)/(3+5 + 5+3) = 23. [Kulsha]
The largest prime with its least quadratic non-residue greater than sqrt(p). [Nagell]
The smallest prime that is both preceded and followed by a prime number of successive composites. [Beedassy]
Cyclotomic rings are formed by adjoining the n roots of unity to the integers. Montgomery and Uchida independently showed that the
first of these rings to have class number greater than one is formed by adjoining the 23rd roots of unity. [Bonan]
There are only 23 odd abundant numbers below 104.
23 is the smallest prime of the form 10*p + 3 that is not the sum of
two squares, where p is prime. [Murton]
11111111111111111111111 (23 ones) is a repunit prime.
11111 * 111111 + 11111111111 + 1 (23 ones) is prime. [Fougeron]
2n + 3n is prime for n = 0, 1 and 2. [Trotter]
Sherlock Holmes and Doctor Watson lived at 221b Baker Street for a period of 23 years. [Haga]
There are 23 discs in the human spine. [McCranie]
The top speed of an American crow is 23 miles per hour. [Stidham]
23! is the least factorial in which the digits 0 through 9 appear at least once. [Das]
W is the 23rd letter of the modern English alphabet. Have you ever noticed that it has 2 points down and 3 points up?
23 is the only prime of the form p*q + p + q and p*q - p - q, where p and q are two successive primes (3*5 + 3 + 5 = 5*7 - 5 - 7 = 23. [Teofilatto]
There are 23 definitions in Book I of Euclid's Elements.
(23) = 32. [Caldwell]
23 = 5 + 7 + 11. Do you see the first five consecutive primes? [La Haye]
23 is the smallest prime number with consecutive digits. [Capelle]
23 = 3 times the third prime + twice the second prime + once the first prime. [Murthy]
2! + 3! = 23. [Murthy]
23 = - (22 - 33). [Murthy]
The smallest prime which differs from its successor by 6. [Murthy]
Thrice three and twenty for pleasure true and plenty. [Croll]
The smallest prime of form pp - qq, where p and q are primes. [Murthy]
Smallest prime p such that 90*p+11, 90*p+13, 90*p+17, 90*p+19 are all primes. [Russo]
The sum of the forth powers of the first 23 primes is prime. [Patterson]
23 is the smallest prime number that is equal to the product plus sum of twin primes, i.e., 3*5 + (3+5) = 23. [Wagler]
At the height of his career, Professor John F. Nash, Jr., interrupted a lecture to announce that a photo of Pope John XXIII on the cover of LIFE magazine was actually himself (Nash) in disguise and that he knew this because 23 was his favorite prime number. [Hageman]
The smallest multidigit tetranacci prime: a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4). [Russo]
The smallest prime p that divides the number of digits of p!. [Russo]
The largest integer that cannot be expressed as the sum of two squareful numbers. A number is squareful (or non-squarefree) if it contains at least one square in its prime factorization. [Rupinski]
The sum of the square roots of the first 23 primes is very near the 32nd prime. [Rupinski]
In a room of just 23 people, a greater than 50% chance exists that two of the people will share a common birthday.
Archbishop Ussher
(1581-1656), Primate of All Ireland, argued that the world was created on October 23, 4004 B.C. [Delval]
In the Charles Dickens novel A Tale of Two Cities, each beheading was counted down. Sidney Carton, the insolent, indifferent, and alcoholic attorney, was guillotine victim number 23. [Nunes]
"Twenty-three, skidoo!" is an American catch phrase of unknown origin.
Julius Caesar was stabbed 23 times when he was assassinated.
23 is the second Woodall prime.
"The Immortal Game" of chess, played in London on June 21, 1851, between Adolf Anderssen and Lionel Kieseritzky, ended after Anderssen sacrificed a bishop, two rooks, and his queen to deliver checkmate in 23 moves. Below is a record of this in algebraic notation:
1. e4 e5 2. f4 exf4 3. Bc4 Qh4+ 4. Kf1 b5 5. Bxb5 Nf6 6. Nf3 Qh6 7. d3 Nh5 8. Nh4 Qg5 9. Nf5 c6 10. g4 Nf6 11. Rg1 cxb5 12. h4 Qg6 13. h5 Qg5 14. Qf3 Ng8 15. Bxf4 Qf6 16. Nc3 Bc5 17. Nd5 Qxb2 18. Bd6 Bxg1 19. e5 Qxa1+ 20. Ke2 Na6 21. Nxg7+ Kd8 22. Qf6+ Nxf6 23. Be7 mate
A factorial expression involving the digits of 23 is 1! + (2! + 2!) + (3! + 3! + 3!). [Capelle]
There are exactly 23 nonisomorphic trees with 2^3 vertices. [Patterson]
The pseudoscientific "biorhythm theory" claims everyone has a 23-day physical cycle that influences their general physical condition.
One 2 and one 3 (23) divides two 2's and three 3's (22333). [De Geest]
2^23 + 3^23 + 2*3 is prime. [Laurv]
There are 23 primes which can not be written as a sum of (nonunit) cubes. Note that 23 is the largest prime which cannot be written as a sum of (nonunit) squares. [Hartley]
There are 23 distinct pairs of primes less than 1000 that sum to 1000. [Patterson]
The world's fastest human can average 23 miles/hour in the 100 meter dash. [Adrion]
23 differs from its reversal by 3^2. [Markowitz]
The largest of the six primes which are uniquely expressible as the sum of at most 4 squares. The others are 2, 3, 5, 7, and 11. [Rupinski]
The word hell is found only 23 times in the King James Version of the New Testament, and most of those are by Jesus. [Van Empe]
The Sundial Bridge, a footbridge over the Sacramento River at Redding, California, is just short of 23 feet wide. [Haga]
23 is the only prime of the form p*q + p + q and p*q - p - q, where p and q are twin primes (3*5 + 3 + 5 and 5*7 - 5 - 7 = 23.) [Teofilatto]
23 is the smaller prime factor of 2^11-1, the smallest composite Mersenne number with prime exponent. [Terr]
The smallest Pillai prime.
23 is the first happy number that is not of the form 3n+1. [Axoy]
23 is the only known number p where Rp is a repunit prime, 10^p-p is prime, and p is a primefactor of a Mersenne number with repunit exponent. I.e., 23 is factor of 2^(11)-1). [Luhn]
23*3-32*2 = (3+2)*(3-2). [Losnak]
The primes up to 23 and the squares of primes up to 23 separated by zeros form primes. [Gallardo]
Dr. Pepper is a unique blend of 23 secret flavors. [Dowdy]
23 is 2 (mod 3) and 3 (mod 2). [Losnak]
23 is the smallest and only prime of the form
2x^2 - y^2 and 3x^2 - y^2, where x and y are two consecutive numbers. [Teofilatto]
23 is the smallest prime equal to the sum of three primes in two ways: 5+7+11 = 3+7+13 = 23. [Teofilatto]
To get the largest 23-digit prime one only needs to subtract 23 from 10^23. [De Geest]
23 = (2^2 + 3^3) - (2! + 3!). [Teofilatto]
No one really knows exactly when the great English poet and playwright William Shakespeare (1564-1616) was born, but, traditionally St. George's Day (April 23) has been his accepted birthday. However, we do know that he died on this date. [Dowdy]
The only prime in a sequence of six numbers that regularly occurred in the first season of the television series Lost. [Hartley]
The smaller prime of the smallest set of two consecutive multidigit primes (23, 29) whose sum of digits (5, 11) is another set of two distinct primes. [Gupta]
The first number with a prime number of digits, all digits
prime, and the sum of all digits being prime. [Dickman]
The smallest prime number string where each substring is prime. [Banerjee]
23 is the largest row of Pascal's triangle all of whose
entries are square-free. [Beedassy]
The sum of first 23 primes is 874 (a multiple of 23). Note
that 874 = 23 * 38 and the 23rd prime is 83. [Poo Sung]
If you were able to fold (doubling each time) a standard sheet of writing paper 23 times, it would become over a mile thick. [Rogowski]
October 23 is Mole Day. It is celebrated among chemists in North America from 6:02 A.M. to 6:02 P.M. on 10/23 each year in honor of Avogadro's number, which is approximately 6.02 * 10^23. [Pritesh]
David Bloomberg (Bryan Greenberg) is a penniless
23-year-old painter when he meets the fourteen-years-older
Rafi Gardet (Uma Thurman) in the movie Prime. [Opao]
The only possible binary "perfect code" that corrects two or more errors is the three error correcting Golay code of length 23. [Kerdock]
23 is the smallest prime with a composite number of 1s in
its binary expansion. [Keith]
In the movie "Support Your Local Gunfighter," starring
James Garner, the protagonist has an obsessive compulsion
to risk all his money in roulette on the number 23. It
causes him to consistently lose any significant money he
amasses. He says of the number, "It pulls at me." [Wynn]
The smallest non-reflectable non-strobogrammatic non-invertible non-palindromic non-reversible prime number. [Capelle]
The number of characters in the interjection : "Yeah! Hints on the primes" (a most fitting anagram for "The
Riemann Hypothesis" due to V. Rabin). [Beedassy]
The sum of the first 666 prime numbers divided by 66659. [Honaker]
23 = 2^3 + 3^2 + 2*3. [Hollesen]
The sum of the digits of 23^2+3 is the next prime after 23. [Silva]
Joe the Plumber (Samuel Joseph Wurzelbacher) was mentioned by John McCain and Barack Obama at least 23 times during the presidential debate of October 15, 2008. [ABC News]
The smallest prime p that divides the sum of the first p primes. [Beedassy]
The smallest prime followed by a number of composite
consecutive integers equal to the sum of its digits. [Silva]
The sum of the consecutive primes from 23 to the 23rd prime
is a palindromic prime. [Silva]
There are exactly 23 prime-digit primes below one thousand,
and 23 is one of them (more precisely the nth,
where n is the (prime) sum of its digits). [Beedassy]
There are 23 known natural numbers n such that
2n does not contain the digit
2. Their sum ends with 23, which is one of them. The prime
cases are easy to remember: 2, 3, 23 and ... the 23th
prime! [Capelle]
23 + 2*3, 23 + 2^3, and 23 + 2*3 + 2^3 are the three next primes after 23. [Silva]
The smallest prime which when prefixed to the smallest
pandigital string forms another prime: 230123456789. [Beedassy]
23 = -2^2 + 3^3. [Meller]
23 = 05 + 14 + 23 +
32 + 41 + 50. [Poo Sung]
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