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| Photo credit: Marsha Greer |
89 is the fifth Fibonacci prime.
89 and 97 are the first pair of consecutive primes differing by 8.
The smallest composite-digit prime.
12 * 34567 + 89 is a 9-digital prime expression.
The smallest Sophie Germain prime to start a Cunningham chain of length 6 (1st kind): (89, 179, 359, 719, 1439, 2879).
Two to the power 89, minus one, was first proved prime by a man whose last name was Powers.
89 = 8 + 92.
89 is the smallest circular-digit prime.
Hellin's law states that twins occur once in 89 births, triplets once in 892 births, and quadruplets once in 893 births, and so forth. This approximation came before the advent of fertility methods. [Crown]
22 + 33 + 55 + 77 + 1111 + ... + 8989 is prime. [Crespi de Valldaura]
The reciprocal of the Fibonacci prime number
89 starts out 0.011235... (generating the first five Fibonacci numbers). [Hafen]
The concatenation of all odd primes starting from 89 and
counting in reverse is prime. [Gupta]
The two area codes added in the 1999-2000 time period that overlay the 215 area code in Pennsylvania (Philadelphia area) are both multiples of 89: 267 = 3 * 89 and 445 = 5 * 89. [Litman]
M89 begins with digits 61 89. Note the greatest integer function of the natural log of M89 is 61. [Luhn]
89 contains two consecutive numbers in order. [Das]
(88*99) is congruent to 8*9 (mod 89). [Luhn]
89 is the largest Fibonacci number occurring in natural
floral arrangements as the most common number of petals of
the Michaelmas daisy (asteraceae family). [Beedassy]
The US Air Force 89th Presidential Airlift Group consists of the President's Air Force One airplanes. [Anon]
The smallest prime that is a concatenation of p^q and q^p where p and q are prime. [Murthy]
The smallest multidigit prime p such that the sum of digits raised to the consecutive powers is equal to p itself. [Russo]
89# - 1 is prime. [Dobb]
Hugo Steinhaus (1887-1972) proved that if you take any positive integer, find the sum of the squares of its digits, and then repeat; that you will either come to 1 or the cyclic sequence 145, 42, 20, 4, 16, 37, 58, 89.
89 is the prime among two-digit numbers that requires the most reverse-and-adding to become a palindrome.
The smallest holey prime.
The smallest multidigit prime whose binary (1011001), octal (131) and hexadecimal (59) representations are primes too. [Kik]
89 is the smallest prime (indeed the smallest positive integer) whose square (7921) and cube (704969) are likewise prime upon reversal. [Trotter]
The longest verse in the KJV Bible is Esther 8:9 with 89 plus one words.
The Queenland Legislative Assembly consists of 89 Members.
The height of the pedistal under the Statue of Liberty is 89'. [Patterson]
89 is the larger prime factor of 2^11-1, the smallest composite Mersenne number with prime exponent. [Terr]
The smallest prime for which the sum of all odd primes less than or equal to it is a square. [Astle]
89 is the smallest prime that is changed into a composite number if any digit is deleted. [Astle]
89 = 8*9 + 8+9. [Losnak]
89 is the smallest number whose binary and octal representations are all different and all prime if read in decimal. I.e., 1011001 and 131 are all prime. Besides, 89 itself and the hexadecimal representation 59 are also prime. [Poo Sung]
The smallest prime formed by concatenation of perfect
powers. [Silva]
89 = 9+8+7+6+5+4+3+2+1+2+3+4+5+6+7+8+9. [Silva]
89 is the atomic number of Actinium, the first in the list
of chemical elements alphabetically ordered. Note the
appropriate use of the phrase "atomic number" which
literally means "number that cannot be split." [Beedassy]
The largest prime equal to the sum of its digits plus the
product of its digits. [Silva]
The only two-digit prime p such that 2^p + p is prime. [Silva]
The only two-digit prime formed from composite digits. [Silva]
The only prime formed from unrepeated composite digits. [Silva]
89 = prime(phi(8)*phi(9)) = prime(phi(sigma(89))), so
phi(sigma(89)) = phi(8)*phi(9). [Firoozbakht]
The smallest prime consisting of two consecutive powerful
numbers. [Beedassy]
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