31381812 has 72 divisors (see below), whose sum is σ = 98908992. Its totient is φ = 8150400.

The previous prime is 31381807. The next prime is 31381817. The reversal of 31381812 is 21818313.

It is an interprime number because it is at equal distance from previous prime (31381807) and next prime (31381817).

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31381817) 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, 2889 + ... + 8432.

It is an arithmetic number, because the mean of its divisors is an integer number (1373736).

Almost surely, 2^31381812 is an apocalyptic number.

It is an amenable number.

31381812 is an abundant number, since it is smaller than the sum of its proper divisors (67527180).

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

31381812 is a wasteful number, since it uses less digits than its factorization.

31381812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11349 (or 11344 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 31381812 is about 5601.9471614788. The cubic root of 31381812 is about 315.4225018383.

It can be divided in two parts, 3138 and 1812, that added together give a triangular number (4950 = T₉₉).

The spelling of 31381812 in words is "thirty-one million, three hundred eighty-one thousand, eight hundred twelve".