31981957 has 12 divisors (see below), whose sum is σ = 37717356. Its totient is φ = 27034560.

The previous prime is 31981933. The next prime is 31982033. The reversal of 31981957 is 75918913.

It can be written as a sum of positive squares in 2 ways, for example, as 19633761 + 12348196 = 4431^2 + 3514^2 .

It is a de Polignac number, because none of the positive numbers 2^k-31981957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31981907) 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, 894 + ... + 8047.

It is an arithmetic number, because the mean of its divisors is an integer number (3143113).

Almost surely, 2^31981957 is an apocalyptic number.

31981957 is the 3577-th heptagonal number.

It is an amenable number.

31981957 is a deficient number, since it is larger than the sum of its proper divisors (5735399).

31981957 is an equidigital number, since it uses as much as digits as its factorization.

31981957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9028 (or 9021 counting only the distinct ones).

The product of its digits is 68040, while the sum is 43.

The square root of 31981957 is about 5655.2592336691. The cubic root of 31981957 is about 317.4205294312.

The spelling of 31981957 in words is "thirty-one million, nine hundred eighty-one thousand, nine hundred fifty-seven".