31980921 has 16 divisors (see below), whose sum is σ = 49167744. Its totient is φ = 18111744.

The previous prime is 31980919. The next prime is 31980959. The reversal of 31980921 is 12908913.

It is not a de Polignac number, because 31980921 - 2¹ = 31980919 is a prime.

It is not an unprimeable number, because it can be changed into a prime (31980901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4366 + ... + 9111.

It is an arithmetic number, because the mean of its divisors is an integer number (3072984).

Almost surely, 2^31980921 is an apocalyptic number.

It is an amenable number.

31980921 is a deficient number, since it is larger than the sum of its proper divisors (17186823).

31980921 is a wasteful number, since it uses less digits than its factorization.

31980921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13600.

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 31980921 is about 5655.1676367726. The cubic root of 31980921 is about 317.4171019651.

The spelling of 31980921 in words is "thirty-one million, nine hundred eighty thousand, nine hundred twenty-one".