31139856 has 80 divisors (see below), whose sum is σ = 97523520. Its totient is φ = 9434880.

The previous prime is 31139821. The next prime is 31139863. The reversal of 31139856 is 65893113.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 31139856.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1476 + ... + 8028.

It is an arithmetic number, because the mean of its divisors is an integer number (1219044).

Almost surely, 2^31139856 is an apocalyptic number.

31139856 is a gapful number since it is divisible by the number (36) 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 31139856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48761760).

31139856 is an abundant number, since it is smaller than the sum of its proper divisors (66383664).

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

31139856 is a wasteful number, since it uses less digits than its factorization.

31139856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6581 (or 6569 counting only the distinct ones).

The product of its digits is 19440, while the sum is 36.

The square root of 31139856 is about 5580.3096688266. The cubic root of 31139856 is about 314.6097661965.

The spelling of 31139856 in words is "thirty-one million, one hundred thirty-nine thousand, eight hundred fifty-six".