639997656264 has 48 divisors (see below), whose sum is σ = 1734830529900. Its totient is φ = 213147500544.

The previous prime is 639997656257. The next prime is 639997656289. The reversal of 639997656264 is 462656799936.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 638768592900 + 1229063364 = 799230^2 + 35058^2 .

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a junction number, because it is equal to n+sod(n) for n = 639997656192 and 639997656201.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3771649 + ... + 3937680.

Almost surely, 2^639997656264 is an apocalyptic number.

It is an amenable number.

639997656264 is an abundant number, since it is smaller than the sum of its proper divisors (1094832873636).

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

639997656264 is a wasteful number, since it uses less digits than its factorization.

639997656264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7710494 (or 7710487 counting only the distinct ones).

The product of its digits is 793618560, while the sum is 72.

The spelling of 639997656264 in words is "six hundred thirty-nine billion, nine hundred ninety-seven million, six hundred fifty-six thousand, two hundred sixty-four".