31861920 has 96 divisors (see below), whose sum is σ = 102876480. Its totient is φ = 8284160.

The previous prime is 31861919. The next prime is 31861931. The reversal of 31861920 is 2916813.

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

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 18871 + ... + 20489.

It is an arithmetic number, because the mean of its divisors is an integer number (1071630).

Almost surely, 2^31861920 is an apocalyptic number.

31861920 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 31861920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (51438240).

31861920 is an abundant number, since it is smaller than the sum of its proper divisors (71014560).

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

31861920 is a wasteful number, since it uses less digits than its factorization.

31861920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1678 (or 1670 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 31861920 is about 5644.6363921868. The cubic root of 31861920 is about 317.0229096414.

The spelling of 31861920 in words is "thirty-one million, eight hundred sixty-one thousand, nine hundred twenty".