31957 has 2 divisors, whose sum is σ = 31958. Its totient is φ = 31956.

The previous prime is 31907. The next prime is 31963. The reversal of 31957 is 75913.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30276 + 1681 = 174^2 + 41^2 .

It is an emirp because it is prime and its reverse (75913) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31907) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15978 + 15979.

It is an arithmetic number, because the mean of its divisors is an integer number (15979).

2³¹⁹⁵⁷ is an apocalyptic number.

It is an amenable number.

31957 is a deficient number, since it is larger than the sum of its proper divisors (1).

31957 is an equidigital number, since it uses as much as digits as its factorization.

31957 is an evil number, because the sum of its binary digits is even.

The product of its digits is 945, while the sum is 25.

The square root of 31957 is about 178.7652091432. The cubic root of 31957 is about 31.7337941973.

Subtracting 31957 from its reverse (75913), we obtain a triangular number (43956 = T₂₉₆).

The spelling of 31957 in words is "thirty-one thousand, nine hundred fifty-seven".