 181 (another Prime Pages' Curiosity) Curios: Curios Search:   Participate:  GIMPS has discovered a new largest known prime number: 282589933-1 (24,862,048 digits) 181 is the 9th palindromic prime number. Note that 9 divides 18 and 81, whose sum of digits are both 9. There are 181 digits in 111!. [De Geest] The 181st prime is congruent to 1 (mod 181). [Haga] The prime value of x in the equation x2 = 2(3 * 5) - 7. 181 * 10181 + (10181 - 1) is prime. [Luhn] The sum of the first 181 primes minus 181 is prime. [Gevisier] The sum of the digits of the first 23 primes (2, ..., 83). [Trotter] The 181-digit palindromic number made up of all 7's except for the center nut being 181 (7777...7718177...77777) is a palindromic prime with a palindromic prime decimal length. [Fougeron] The first occurrence of two consecutive primes which are both nontrivial (more than one digit) palindromes: 181, 191. [Murthy] The smallest palindromic prime that remains prime through four iterations of the function f(x) = 2x + 5. [Russo] The smaller of the first occurrence of two successive primes using no prime digits (181, 191). [Murthy] The surface area of a pair Boeing 757 wings in square meters. 181 pennies currently minted in the U.S. weigh within a penny of a pound. 181 is the smallest odd prime (and fifth in all) exponent of 2 dissecting the interval between successive primes, i.e., 2^181 + 165 are both prime with no intervening primes. [King] 181 = 92 + 102, i.e., the sum of two consecutive squares. [Mizuki] No ship of the United States Navy has ever been named USS Haynes. A fictitious USS Haynes (DE-181) was the setting for the surface half of the movie The Enemy Below; her part was played by USS Whitehurst (DE-634). [Haga] The smaller prime in the first multidigit "Gridgeman pair." A Gridgeman pair is two palindromic primes, which differ only in that their middle digits are x and x + 1 respectively. These are named in honor of Norman T. Gridgeman (1912-1995) who conjectured that there are an infinite number of primes in this form. [King] The smallest palindromic prime number whose sum of digits is composite. Note that 181 is also the smallest such that at least one of the digits is composite. [Capelle] 181^2 = 105^3 - 104^3, i.e., a solution to the Diophantine equation z^2 = x^3 - y^3. [Mizuki] It is conjectured that there is always a prime between xa and yb for all integers x, y, a, b > 1, except for the following ten pairs: (23,32), (52,33), (25,62), (112,53), (37,133), (55,562), (1812,215), (433,2822), (463,3122), and (224342,555). [Redmond and Sun] The smallest palindromic prime resulting from the sum of three consecutive emirps (37, 71, 73). [Silva] The smallest prime which is a d-digit palindrome base 10 as well as a d-digit palindrome for some base b different from 10. [Post] Every natural number greater than 181 can be written as sum of cubes of the first two primes. [Capelle] 181 candidates were nominated for the Nobel Peace Prize the year Al Gore won it. [Francis] The smallest prime decimal Goedelization of a theorem from propositional calculus, symbolizing "A is logically equivalent to A." [Post] Only number n such that prime(n) = 6n + 1. [Firoozbakht] The sum of strobogrammatic numbers less than or equal to 181 equals 666. (see OEIS A230833) Can you find another strobogrammatic prime of the form (5n^2+5n+2)/2? [Honaker] "Cosmos: A Spacetime Odyssey" premiered in 181 countries. There are at least 181 Las Bolas Grandes ('The Great Stone Balls' in Spanish) of Costa Rico that survive whole. [Lothrop] The complex vitamin B12 molecule contains a total of 181 atoms. [Newmark] List all the whole numbers less than 1000, that is 0 - 999. The number of whole numbers in the list containing the digit 0 is 181. [Green] 181 is a palindromic Pythagorean prime, equal to the sum of the squares of 10 and 9. [Green] Sri Lanka was ruled by 181 monarchs from the Anuradhapura to Kandy periods. (There are 12 curios for this number that have not yet been approved by an editor.) Prime Curios! © 2000-2019 (all rights reserved)  privacy statement