# 53

This number is a prime.  The prayer of Ave Maria is repeated 53 times in the recitation of the rosary. [Desrosiers] π(53) = 52 - 32. [Caldwell] The number painted on the Volkswagen movie star, "Herbie the Love Bug." The reversal of 53 equals the sum of digits of 533. The primes up to 53 are required to generate the first (5-3) digits of the constant 0.269606351971674 ... . [Honaker] 53 is the smallest prime p such that 1p1, 3p3, 7p7 and 9p9 are all prime. [Dale] 253 * 53# - 1 is prime. [Boland] The month and day are simultaneously prime a total of 53 times in a leap year. 53 is the smallest prime factor of 1111111111111 (13 ones). [Astle] π(35) = 53. [Firoozbakht] If A = 1, B = 4, C = 5, D = 2, ... , Z = 9, (using the 2nd, 3rd, 5th, 7th, ..., 101st digits of π), then 'PRIME NUMBER' is a prime number. [Homewood] 53 is thought to be the smallest prime that is not the sum or difference between powers of the first two prime numbers. [Aebi] 53 in decimal is 35 in hexadecimal. [Nigrine] The Late Diana, Princess of Wales, was on the cover of People magazine 53 times. [Numberland] The smallest multidigit balanced prime. [Russo] The chance that no pair of 53 people in a room have the same birthday is approximately 1/53. [ApSimon] 53 is the smallest prime of the form 10*p + 3 that is the sum of two squares, where p is an odd prime. [Murton] The period of 1/53 is one-quarter of the maximum length possible. [Wells] 2^2 + 7^2 = 53. [La Haye] 53 is formed by the concatenation of the smallest twin primes in reverse order. [Gupta] The sums of five, seven, and eleven consecutive Lucas numbers starting from the 53rd Lucas number, 119218851371, are primes. I.e., L(53)+...+L(57), L(53)+...+L(59), and L(53)+...+L(63) are all prime. This is the smallest Lucas number with such property. [Opao] The website address for Fifth Third Bank is www.53.com. (53!/35!)+1 is prime. [Patterson] The smallest prime with a prime ASCII code: 3533 (in base 16) = 13619, that is prime in base ten, too. [Necula] 53 is the sum of 5 consecutive primes with average difference 3. [Coppoletta] The number (53#)2 + 1 is prime. [Patterson] M53 was rediscovered in a prime year (1777). [McAlee] During the Tokugawa Period in Japan, the long road from Kyoto to Edo (now Tokyo), had 53 rest stops along the way. [Haga] The Platonic Realms Math Store offers a downloadable list of 53 Latin terms and phrases commonly used in mathematics. The smallest prime that splits into a prime and the corresponding prime subscript (5 = p3). [Beedassy] ATM (Asynchronous Transfer Mode) is a high-speed network protocol composed of 53 byte "cells." The prime 53 figured in the 1945 WWII battle for Iwo Jima. Task Force 53 brought the 71000 soldiers and 41000 marines. The officer commanding the Japanese troops was Lt. Gen. Tadamichi Kuribayashi, age 53. The average height of a Japanese infantryman was 5'3". Source: History TV Channel. [Haga] 1000^53 - 53 is prime. Note that 53 is the smallest number with this property. [Firoozbakht] The difference between the sum of unitary divisors and the value of the Euler-phi function is iterated, and started at n and a(n) is the length of terminal cycle of iteration involving a high-frequency of the prime number 53. [Labos] The smallest two-digit prime that does not produce a prime by adding a digit to it. (There is no prime '53d'). [Gallardo] The number of member States sitting on The United Nations Commission on Human Rights. [McAlee] 53 = prime( prime(5) + prime(3) ). Note that 53 is the only number with this property. [Firoozbakht] 53 is the first two digits on the AM radio dial. [Cheryl] The p53 gene is a tumor suppressor gene, i.e., its activity stops the formation of tumors. The smallest equal-tempered musical scale that improves on the usual twelve-note scale (in closeness of approximation to the exact musical intervals) has 53 notes. [Keith] In the Dr. Seuss film, "How the Grinch Stole Christmas," the Grinch had been "putting up with" the Christmas celebrations by the Whos of Whoville for 53 years. [Screb] The average U.S. cow produces 53 pounds of milk per day. It is possible to place eight queens on a standard chessboard in which only 53 squares are under attack. Is this the minimum solution? [Madachy] The United States allows the use of 53-foot trailers behind a semi-tractor (called a "prime mover" in Australia). [Caldwell] 253 = 9007199254740992 is the smallest power of 2 with two successive 0's. [Beedassy] The smallest prime Takeuchi number. [Post] Conjectured largest prime p such that there are no twin primes between p^2 and (p+1)^2. [Post] The angle having a secant of 5/3 is very close to 53 degrees. [Beedassy] 53^7 = 1174711139837 and 1+1+7+4+7+1+1+1+3+9+8+3+7 = 53. [Alvarado] "They're talking to us," Reacher said. "Fifty-three is a prime number." (from the novel Bad Luck and Trouble by Lee Child) [Reynolds] The floor function of e^π^phi, where phi is the golden ratio. [Firoozbakht] The largest known prime p such that 2p does not contain the digit 3. It ends with the digit 3, the smallest odd prime with this property. [Capelle] The largest known prime number p such that p! doesn't contain 5! in binary representation. [Capelle] 53 = prime(5*3) + π(5*3). It is the only known prime with this property. [Firoozbakht] The smallest prime p such that reversal(p*reversal(p)) is prime. [Firoozbakht] The largest known natural number that can be expressed as the sum of three nonnegative triangular numbers in exactly one way. [Capelle] The smallest odd prime distance of Fibonacci(n) to the closest prime which is not Fibonacci(n) itself. In this case, n = 9. Fibonacci(9) = 34, which is distance 3 from both 31 and 37. [Post] The only prime consisting of two prime digits whose sum is the cube of their difference. [Beedassy] Melbourne's 53-point win over Geelong in 1939 is the largest winning margin in VFL/AFL football by a team than won only one of the four quarters. The first bisexual prime, i.e., sharing two pairs of sexy primes. [Silva] This number is an emirp in 11 straight bases, from base 30 through base 40. Does any other number have such a string of bases attached to it? [Merickel] There are 53 distinct ways of constructing hole-free pentagonal shapes with the seven pieces of a tangram. [Beedassy] In the movie "Superman III," the first Bingo ball drawn by Perry White in the newsroom is 53. Barbie turned 53 years old today (March 9, 2012). [Garrett] Doubling 53 places a 0 between the digits of its index, i.e., 2*(5+3). [Merickel] The smallest prime that is the arithmetic average of three consecutive double-digit primes (47, 53, 59). [Loungrides] The smallest prime that is the arithmetic average of seven consecutive primes (41, 43, 47, 53, 59, 61, 67). [Loungrides] The moon's Tycho Crater is about 53 miles in diameter. After 53 hours' non-stop swimming, Diana Nyad reached Key West, Florida, escorted by boats and her team of 35 (reversal of 53) people. [Post] 53 is the largest prime less than a googol of form 2*x^x-1 where x is an integer. (7 is the smallest prime of the same form). [Loungrides] The larger of only two non-titanic primes of form 2*p^p-1 for p a prime, (p=3). The previous is 7 for p=2. [Loungrides] 53 is the smallest super-prime leader: right-truncatable prime p with property that appending any single decimal digit to p does not produce a prime. [Post] The number of letters in the the following statement that transcribes the Fundamental Theorem of Arithmetic: "Any integer beyond unity is either a prime or a product of primes." [Beedassy] In the British comedy 'Goodnight Sweetheart' Gary Sparrow (played by Nicholas Lyndhurst) travels back in time 53 years. [Homewood] The only known prime that can be represented as the quotient of the division (q*r*s+1)/p where (p, q, r, s) are four successive primes, p < q < r < s, i.e., (p, q, r, s) = (2, 3, 5, 7). [Loungrides] Prime Number Magazine features distinctive poetry, short fiction, and a 53-word story contest. If A = 3, B = 1, C = 4, D = 1, ... , (using the digits of π), then 'FIFTY THREE' = 53. [Homewood] The number of "green bars" in the painting Woman with Prime Numbers by Joe Rebholz. How many blue bars? The famous Chouan Georges Cadoudal was arrested in a fiacre with the licence number 53. [Olry] There are 53 prime numbers below a thousand where the sum of the squared digits of that prime is also prime. The first being 11 = 1^2 + 1^2 = 2 and the last 997 = 9^2 + 9^2 + 7^2 = 211. [Homewood] There are exactly 53 sevens in the first 53 seventh powers. [Gaydos] The prime digits of the prime number 53 come in handy on the front cover of "NUMBER5 ARE FOR3VER: Mathematical Facts and Curiosities" by Liz Strachan. The are no twin primes between 53^2 and (53 + 1)^2. [Jung] 53 (exactly half) of the first 106 prime numbers each has at least one prime cousin. [Gaydos] The highest prime factor in a list of 48 semiprimes (by A. W. Johnson, 1978) the sum of whose reciprocals forms an Egyptian fraction of unity: (1/2*3 + 1/2*5 + 1/2*7 + 1/2*11 + 1/2*13 + 1/2*17 + 1/2*19 + 1/2*23 + 1/2*29 + 1/2*31 + 1/2*41 + 1/2*43) + (1/3*5 + 1/3*7 + 1/3*11 + 1/3*13 + 1/3*17 + 1/3*19 + 1/3*23 + 1/3*29 + 1/3*31 + 1/3*41) + (1/5*7 + 1/5*11 + 1/5*13 + 1/5*17 + 1/5*19 + 1/5*23 + 1/5*31 + 1/5*43 + 1/5*53) + (1/7*11 + 1/7*13 + 1/7*17 + 1/7*19 + 1/7*29 + 1/7*41) + (1/11*17 + 1/11*19 + 1/11*29) + (1/13*17 + 1/13*19 + 1/13*23 + 1/13*53) + (1/17*19 + 1/17*23 + 1/17*43 + 1/17*53) = 1. [Beedassy] A mutated protein called p53 is implicated in half of all common cancers. [Kaku] The lagging strand of DNA runs in the 5 prime to 3 prime direction. [Okazaki] The event that Americans commonly call the "First Thanksgiving" was celebrated by 53 Pilgrims after their first harvest in the New World. [Winslow] Executive Order 53 directs all Virginians to stay home except in extremely limited circumstances, due to novel coronavirus. There are 53 six-digit cubes. [Gaydos]

(There are 23 curios for this number that have not yet been approved by an editor.)