31995640 has 16 divisors (see below), whose sum is σ = 71990280. Its totient is φ = 12798240.

The previous prime is 31995631. The next prime is 31995643. The reversal of 31995640 is 4659913.

It is a self number, because there is not a number n which added to its sum of digits gives 31995640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31995643) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 399906 + ... + 399985.

Almost surely, 2^31995640 is an apocalyptic number.

It is an amenable number.

31995640 is an abundant number, since it is smaller than the sum of its proper divisors (39994640).

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

31995640 is a wasteful number, since it uses less digits than its factorization.

31995640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 799902 (or 799898 counting only the distinct ones).

The product of its (nonzero) digits is 29160, while the sum is 37.

The square root of 31995640 is about 5656.4688631690. The cubic root of 31995640 is about 317.4657908458.

It can be divided in two parts, 31995 and 640, that multiplied together give a triangular number (20476800 = T₆₃₉₉).

The spelling of 31995640 in words is "thirty-one million, nine hundred ninety-five thousand, six hundred forty".