638844865518 has 16 divisors (see below), whose sum is σ = 1277778712320. Its totient is φ = 212933458296.

The previous prime is 638844865513. The next prime is 638844865627. The reversal of 638844865518 is 815568448836.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638844865513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3614038 + ... + 3786681.

It is an arithmetic number, because the mean of its divisors is an integer number (79861169520).

Almost surely, 2^638844865518 is an apocalyptic number.

638844865518 is an abundant number, since it is smaller than the sum of its proper divisors (638933846802).

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

638844865518 is a wasteful number, since it uses less digits than its factorization.

638844865518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7415111.

The product of its digits is 176947200, while the sum is 66.

The spelling of 638844865518 in words is "six hundred thirty-eight billion, eight hundred forty-four million, eight hundred sixty-five thousand, five hundred eighteen".