638557936813 has 16 divisors (see below), whose sum is σ = 664886592000. Its totient is φ = 612603743040.

The previous prime is 638557936733. The next prime is 638557936837. The reversal of 638557936813 is 318639755836.

It is a cyclic number.

It is not a de Polignac number, because 638557936813 - 2³⁷ = 501118983341 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638557937813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2215270 + ... + 2486872.

It is an arithmetic number, because the mean of its divisors is an integer number (41555412000).

Almost surely, 2^638557936813 is an apocalyptic number.

It is an amenable number.

638557936813 is a deficient number, since it is larger than the sum of its proper divisors (26328655187).

638557936813 is a wasteful number, since it uses less digits than its factorization.

638557936813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 272292.

The product of its digits is 97977600, while the sum is 64.

The spelling of 638557936813 in words is "six hundred thirty-eight billion, five hundred fifty-seven million, nine hundred thirty-six thousand, eight hundred thirteen".