31720664 has 16 divisors (see below), whose sum is σ = 61527600. Its totient is φ = 15313312.

The previous prime is 31720651. The next prime is 31720669. The reversal of 31720664 is 46602713.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31720669) 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, 68132 + ... + 68595.

It is an arithmetic number, because the mean of its divisors is an integer number (3845475).

Almost surely, 2^31720664 is an apocalyptic number.

It is an amenable number.

31720664 is a deficient number, since it is larger than the sum of its proper divisors (29806936).

31720664 is a wasteful number, since it uses less digits than its factorization.

31720664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136762 (or 136758 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 29.

The square root of 31720664 is about 5632.1100841514. The cubic root of 31720664 is about 316.5537212472.

The spelling of 31720664 in words is "thirty-one million, seven hundred twenty thousand, six hundred sixty-four".