638766864 has 40 divisors (see below), whose sum is σ = 1833498720. Its totient is φ = 212922144.

The previous prime is 638766859. The next prime is 638766899. The reversal of 638766864 is 468667836.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 638766864.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 738882 + ... + 739745.

It is an arithmetic number, because the mean of its divisors is an integer number (45837468).

Almost surely, 2^638766864 is an apocalyptic number.

It is an amenable number.

638766864 is an abundant number, since it is smaller than the sum of its proper divisors (1194731856).

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

638766864 is a wasteful number, since it uses less digits than its factorization.

638766864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1478644 (or 1478632 counting only the distinct ones).

The product of its digits is 6967296, while the sum is 54.

The square root of 638766864 is about 25273.8375400334. The cubic root of 638766864 is about 861.2200387004.

The spelling of 638766864 in words is "six hundred thirty-eight million, seven hundred sixty-six thousand, eight hundred sixty-four".