31391136 has 144 divisors (see below), whose sum is σ = 106614144. Its totient is φ = 8566272.

The previous prime is 31391131. The next prime is 31391147. The reversal of 31391136 is 63119313.

It is a tau number, because it is divible by the number of its divisors (144).

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

It is not an unprimeable number, because it can be changed into a prime (31391131) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 46030 + ... + 46706.

It is an arithmetic number, because the mean of its divisors is an integer number (740376).

Almost surely, 2^31391136 is an apocalyptic number.

31391136 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 31391136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (53307072).

31391136 is an abundant number, since it is smaller than the sum of its proper divisors (75223008).

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

31391136 is a wasteful number, since it uses less digits than its factorization.

31391136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 723 (or 712 counting only the distinct ones).

The product of its digits is 1458, while the sum is 27.

The square root of 31391136 is about 5602.7793103066. The cubic root of 31391136 is about 315.4537376401.

The spelling of 31391136 in words is "thirty-one million, three hundred ninety-one thousand, one hundred thirty-six".