81657 has 12 divisors (see below), whose sum is σ = 121264. Its totient is φ = 52920.

The previous prime is 81649. The next prime is 81667. The reversal of 81657 is 75618.

81657 is a `hidden beast` number, since 8 + 1 + 657 = 666.

81657 is nontrivially palindromic in base 2.

It is not a de Polignac number, because 81657 - 2³ = 81649 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81657.

It is not an unprimeable number, because it can be changed into a prime (81637) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 282 + ... + 492.

2⁸¹⁶⁵⁷ is an apocalyptic number.

It is an amenable number.

81657 is a deficient number, since it is larger than the sum of its proper divisors (39607).

81657 is a wasteful number, since it uses less digits than its factorization.

81657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260 (or 257 counting only the distinct ones).

The product of its digits is 1680, while the sum is 27.

The square root of 81657 is about 285.7568896807. The cubic root of 81657 is about 43.3841547060.

The spelling of 81657 in words is "eighty-one thousand, six hundred fifty-seven".