31231640 has 32 divisors (see below), whose sum is σ = 76660560. Its totient is φ = 11356800.

The previous prime is 31231639. The next prime is 31231667. The reversal of 31231640 is 4613213.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35051 + ... + 35930.

Almost surely, 2^31231640 is an apocalyptic number.

It is an amenable number.

31231640 is an abundant number, since it is smaller than the sum of its proper divisors (45428920).

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

31231640 is a wasteful number, since it uses less digits than its factorization.

31231640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71003 (or 70999 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 31231640 is about 5588.5275341542. The cubic root of 31231640 is about 314.9185646546.

Adding to 31231640 its reverse (4613213), we get a palindrome (35844853).

The spelling of 31231640 in words is "thirty-one million, two hundred thirty-one thousand, six hundred forty".