31331328 has 176 divisors, whose sum is σ = 100614144. Its totient is φ = 8478720.

The previous prime is 31331327. The next prime is 31331351. The reversal of 31331328 is 82313313.

It is a super-2 number, since 2×31331328² = 1963304228487168, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

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

Its product of digits (1296) is a multiple of the sum of its prime factors (108).

It is a junction number, because it is equal to n+sod(n) for n = 31331298 and 31331307.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31331327) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 666601 + ... + 666647.

Almost surely, 2^31331328 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 31331328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50307072).

31331328 is an abundant number, since it is smaller than the sum of its proper divisors (69282816).

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

31331328 is a wasteful number, since it uses less digits than its factorization.

31331328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108 (or 90 counting only the distinct ones).

The product of its digits is 1296, while the sum is 24.

The square root of 31331328 is about 5597.4394145895. The cubic root of 31331328 is about 315.2532707339.

It can be divided in two parts, 3 and 1331328, that added together give a palindrome (1331331).

The spelling of 31331328 in words is "thirty-one million, three hundred thirty-one thousand, three hundred twenty-eight".