31291920 has 200 divisors, whose sum is σ = 118831680. Its totient is φ = 7568640.

The previous prime is 31291903. The next prime is 31291943. The reversal of 31291920 is 2919213.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

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 39 ways as a sum of consecutive naturals, for example, 71061 + ... + 71499.

Almost surely, 2^31291920 is an apocalyptic number.

31291920 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 31291920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (59415840).

31291920 is an abundant number, since it is smaller than the sum of its proper divisors (87539760).

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

31291920 is a wasteful number, since it uses less digits than its factorization.

31291920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 475 (or 460 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 31291920 is about 5593.9181259650. The cubic root of 31291920 is about 315.1210419178.

The spelling of 31291920 in words is "thirty-one million, two hundred ninety-one thousand, nine hundred twenty".