31686912 has 108 divisors (see below), whose sum is σ = 96854940. Its totient is φ = 9928704.

The previous prime is 31686901. The next prime is 31686917. The reversal of 31686912 is 21968613.

It can be written as a sum of positive squares in 2 ways, for example, as 26378496 + 5308416 = 5136^2 + 2304^2 .

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 not an unprimeable number, because it can be changed into a prime (31686917) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 38764 + ... + 39572.

It is an arithmetic number, because the mean of its divisors is an integer number (896805).

Almost surely, 2^31686912 is an apocalyptic number.

31686912 is a gapful number since it is divisible by the number (32) 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 31686912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48427470).

31686912 is an abundant number, since it is smaller than the sum of its proper divisors (65168028).

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

31686912 is a wasteful number, since it uses less digits than its factorization.

31686912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 848 (or 831 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 31686912 is about 5629.1128963630. The cubic root of 31686912 is about 316.4414063122.

The spelling of 31686912 in words is "thirty-one million, six hundred eighty-six thousand, nine hundred twelve".