31909920 has 96 divisors (see below), whose sum is σ = 114887808. Its totient is φ = 7292928.

The previous prime is 31909919. The next prime is 31909937. The reversal of 31909920 is 2990913.

It is a tau number, because it is divible by the number of its divisors (96).

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 1389 + ... + 8108.

It is an arithmetic number, because the mean of its divisors is an integer number (1196748).

Almost surely, 2^31909920 is an apocalyptic number.

31909920 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31909920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (57443904).

31909920 is an abundant number, since it is smaller than the sum of its proper divisors (82977888).

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

31909920 is a wasteful number, since it uses less digits than its factorization.

31909920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9522 (or 9514 counting only the distinct ones).

The product of its (nonzero) digits is 4374, while the sum is 33.

The square root of 31909920 is about 5648.8866159625. The cubic root of 31909920 is about 317.1820281600.

The spelling of 31909920 in words is "thirty-one million, nine hundred nine thousand, nine hundred twenty".