638900657 has 16 divisors (see below), whose sum is σ = 662618112. Its totient is φ = 615684240.

The previous prime is 638900629. The next prime is 638900687. The reversal of 638900657 is 756009836.

It is a cyclic number.

It is not a de Polignac number, because 638900657 - 2⁸ = 638900401 is a prime.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638900627) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1311668 + ... + 1312154.

It is an arithmetic number, because the mean of its divisors is an integer number (41413632).

Almost surely, 2^638900657 is an apocalyptic number.

It is an amenable number.

638900657 is a deficient number, since it is larger than the sum of its proper divisors (23717455).

638900657 is a wasteful number, since it uses less digits than its factorization.

638900657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 908.

The product of its (nonzero) digits is 272160, while the sum is 44.

The square root of 638900657 is about 25276.4842689801. The cubic root of 638900657 is about 861.2801634893.

The spelling of 638900657 in words is "six hundred thirty-eight million, nine hundred thousand, six hundred fifty-seven".