31997696639 has 2 divisors, whose sum is σ = 31997696640. Its totient is φ = 31997696638.

The previous prime is 31997696629. The next prime is 31997696651. The reversal of 31997696639 is 93669679913.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31997696639 - 2²⁰ = 31996648063 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31997696629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15998848319 + 15998848320.

It is an arithmetic number, because the mean of its divisors is an integer number (15998848320).

Almost surely, 2^31997696639 is an apocalyptic number.

31997696639 is a deficient number, since it is larger than the sum of its proper divisors (1).

31997696639 is an equidigital number, since it uses as much as digits as its factorization.

31997696639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 89282088, while the sum is 68.

The spelling of 31997696639 in words is "thirty-one billion, nine hundred ninety-seven million, six hundred ninety-six thousand, six hundred thirty-nine".