31991868 has 24 divisors (see below), whose sum is σ = 82942160. Its totient is φ = 10663920.

The previous prime is 31991867. The next prime is 31991879. The reversal of 31991868 is 86819913.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31991863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 148003 + ... + 148218.

Almost surely, 2^31991868 is an apocalyptic number.

It is an amenable number.

31991868 is an abundant number, since it is smaller than the sum of its proper divisors (50950292).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31991868 is a wasteful number, since it uses less digits than its factorization.

31991868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296234 (or 296226 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 31991868 is about 5656.1354297789. The cubic root of 31991868 is about 317.4533148957.

The spelling of 31991868 in words is "thirty-one million, nine hundred ninety-one thousand, eight hundred sixty-eight".