81157 has 2 divisors, whose sum is σ = 81158. Its totient is φ = 81156.

The previous prime is 81131. The next prime is 81163. The reversal of 81157 is 75118.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64516 + 16641 = 254^2 + 129^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81157 is a prime.

81157 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40578 + 40579.

It is an arithmetic number, because the mean of its divisors is an integer number (40579).

2⁸¹¹⁵⁷ is an apocalyptic number.

It is an amenable number.

81157 is a deficient number, since it is larger than the sum of its proper divisors (1).

81157 is an equidigital number, since it uses as much as digits as its factorization.

81157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 280, while the sum is 22.

The square root of 81157 is about 284.8806767754. The cubic root of 81157 is about 43.2954237813.

It can be divided in two parts, 811 and 57, that added together give a palindrome (868).

The spelling of 81157 in words is "eighty-one thousand, one hundred fifty-seven".