31387920 has 40 divisors (see below), whose sum is σ = 97303296. Its totient is φ = 8370048.

The previous prime is 31387913. The next prime is 31387927. The reversal of 31387920 is 2978313.

It is an interprime number because it is at equal distance from previous prime (31387913) and next prime (31387927).

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (31387927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 65152 + ... + 65631.

Almost surely, 2^31387920 is an apocalyptic number.

31387920 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

31387920 is an abundant number, since it is smaller than the sum of its proper divisors (65915376).

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

31387920 is a wasteful number, since it uses less digits than its factorization.

31387920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130799 (or 130793 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 31387920 is about 5602.4923025382. The cubic root of 31387920 is about 315.4429646004.

The spelling of 31387920 in words is "thirty-one million, three hundred eighty-seven thousand, nine hundred twenty".