31657 has 2 divisors, whose sum is σ = 31658. Its totient is φ = 31656.

The previous prime is 31649. The next prime is 31663. The reversal of 31657 is 75613.

31657 is nontrivially palindromic in base 9.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26896 + 4761 = 164^2 + 69^2 .

It is a cyclic number.

It is not a de Polignac number, because 31657 - 2³ = 31649 is a prime.

It is a nialpdrome in base 14.

It is not a weakly prime, because it can be changed into another prime (31607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15828 + 15829.

It is an arithmetic number, because the mean of its divisors is an integer number (15829).

2³¹⁶⁵⁷ is an apocalyptic number.

It is an amenable number.

31657 is a deficient number, since it is larger than the sum of its proper divisors (1).

31657 is an equidigital number, since it uses as much as digits as its factorization.

31657 is an evil number, because the sum of its binary digits is even.

The product of its digits is 630, while the sum is 22.

The square root of 31657 is about 177.9241411389. The cubic root of 31657 is about 31.6341802883.

Subtracting 31657 from its reverse (75613), we obtain a triangular number (43956 = T₂₉₆).

It can be divided in two parts, 3165 and 7, that multiplied together give a triangular number (22155 = T₂₁₀).

The spelling of 31657 in words is "thirty-one thousand, six hundred fifty-seven".