31139920 has 80 divisors (see below), whose sum is σ = 87637248. Its totient is φ = 10045440.

The previous prime is 31139893. The next prime is 31139929. The reversal of 31139920 is 2993113.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31139929) by changing a digit.

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, 7885 + ... + 11155.

Almost surely, 2^31139920 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31139920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43818624).

31139920 is an abundant number, since it is smaller than the sum of its proper divisors (56497328).

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

31139920 is a wasteful number, since it uses less digits than its factorization.

31139920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3308 (or 3302 counting only the distinct ones).

The product of its (nonzero) digits is 1458, while the sum is 28.

The square root of 31139920 is about 5580.3154032725. The cubic root of 31139920 is about 314.6099817296.

The spelling of 31139920 in words is "thirty-one million, one hundred thirty-nine thousand, nine hundred twenty".