31607991 has 6 divisors (see below), whose sum is σ = 45656000. Its totient is φ = 21071988.

The previous prime is 31607971. The next prime is 31608013. The reversal of 31607991 is 19970613.

It is a de Polignac number, because none of the positive numbers 2^k-31607991 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 (31607921) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1755991 + ... + 1756008.

Almost surely, 2^31607991 is an apocalyptic number.

31607991 is a deficient number, since it is larger than the sum of its proper divisors (14048009).

31607991 is a wasteful number, since it uses less digits than its factorization.

31607991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3512005 (or 3512002 counting only the distinct ones).

The product of its (nonzero) digits is 10206, while the sum is 36.

The square root of 31607991 is about 5622.0984516460. The cubic root of 31607991 is about 316.1784729946.

The spelling of 31607991 in words is "thirty-one million, six hundred seven thousand, nine hundred ninety-one".