The nth Prime Page will now find any of the first 2.623˙1015 primes or π(x) for x up to 1017.
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]
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 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 of Boeing 757 wings in square meters.
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]
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]
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]
(There are 11 curios for this number that have not yet been approved by an editor.)
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