131 (number)


131 is the natural number following 130 and preceding 132.

In mathematics

131 is a Sophie Germain prime, an irregular prime, the second 3-digit palindromic prime, and also a permutable prime with 113 and 311. It can be expressed as the sum of three consecutive primes, 131 = 41 + 43 + 47. 131 is an Eisenstein prime with no imaginary part and real part of the form. Because the next odd number, 133, is a semiprime, 131 is a Chen prime. 131 is an Ulam number.
131 is a full reptend prime in base 10. The decimal expansion of 1/131 repeats the digits 007633587786259541984732824427480916030534351145038167938931 297709923664122137404580152671755725190839694656488549618320 6106870229 indefinitely.

In the military

131 is also: