31997988 has 36 divisors (see below), whose sum is σ = 88237968. Its totient is φ = 9696240.

The previous prime is 31997971. The next prime is 31997989. The reversal of 31997988 is 88979913.

It is a tau number, because it is divible by the number of its divisors (36).

It is not an unprimeable number, because it can be changed into a prime (31997989) 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, 40006 + ... + 40797.

Almost surely, 2^31997988 is an apocalyptic number.

It is an amenable number.

31997988 is an abundant number, since it is smaller than the sum of its proper divisors (56239980).

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

31997988 is a wasteful number, since it uses less digits than its factorization.

31997988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80824 (or 80819 counting only the distinct ones).

The product of its digits is 979776, while the sum is 54.

The square root of 31997988 is about 5656.6764093414. The cubic root of 31997988 is about 317.4735563981.

It can be divided in two parts, 3 and 1997988, that added together give a palindrome (1997991).

The spelling of 31997988 in words is "thirty-one million, nine hundred ninety-seven thousand, nine hundred eighty-eight".