31139928 has 24 divisors (see below), whose sum is σ = 84337500. Its totient is φ = 10379952.

The previous prime is 31139893. The next prime is 31139929. The reversal of 31139928 is 82993113.

It is a tau number, because it is divible by the number of its divisors (24).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 31139892 and 31139901.

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 polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 216178 + ... + 216321.

Almost surely, 2^31139928 is an apocalyptic number.

It is an amenable number.

31139928 is an abundant number, since it is smaller than the sum of its proper divisors (53197572).

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

31139928 is a wasteful number, since it uses less digits than its factorization.

31139928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 432511 (or 432504 counting only the distinct ones).

The product of its digits is 11664, while the sum is 36.

The square root of 31139928 is about 5580.3161200778. The cubic root of 31139928 is about 314.6100086712.

It can be divided in two parts, 3113 and 9928, that added together give a triangular number (13041 = T₁₆₁).

The spelling of 31139928 in words is "thirty-one million, one hundred thirty-nine thousand, nine hundred twenty-eight".