31521864 has 64 divisors (see below), whose sum is σ = 86688000. Its totient is φ = 9472320.

The previous prime is 31521863. The next prime is 31521883. The reversal of 31521864 is 46812513.

It is not an unprimeable number, because it can be changed into a prime (31521863) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36267 + ... + 37125.

It is an arithmetic number, because the mean of its divisors is an integer number (1354500).

Almost surely, 2^31521864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31521864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43344000).

31521864 is an abundant number, since it is smaller than the sum of its proper divisors (55166136).

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

31521864 is a wasteful number, since it uses less digits than its factorization.

31521864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1018 (or 1014 counting only the distinct ones).

The product of its digits is 5760, while the sum is 30.

The square root of 31521864 is about 5614.4335422196. The cubic root of 31521864 is about 315.8910322356.

It can be divided in two parts, 31521 and 864, that added together give a triangular number (32385 = T₂₅₄).

The spelling of 31521864 in words is "thirty-one million, five hundred twenty-one thousand, eight hundred sixty-four".