31978728 has 48 divisors (see below), whose sum is σ = 86879520. Its totient is φ = 10626336.

The previous prime is 31978699. The next prime is 31978733. The reversal of 31978728 is 82787913.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 35775 + ... + 36657.

It is an arithmetic number, because the mean of its divisors is an integer number (1809990).

Almost surely, 2^31978728 is an apocalyptic number.

It is an amenable number.

31978728 is an abundant number, since it is smaller than the sum of its proper divisors (54900792).

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

31978728 is a wasteful number, since it uses less digits than its factorization.

31978728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1398 (or 1391 counting only the distinct ones).

The product of its digits is 169344, while the sum is 45.

The square root of 31978728 is about 5654.9737399921. The cubic root of 31978728 is about 317.4098464766.

The spelling of 31978728 in words is "thirty-one million, nine hundred seventy-eight thousand, seven hundred twenty-eight".