638840887864 has 32 divisors (see below), whose sum is σ = 1215007948800. Its totient is φ = 314841068640.

The previous prime is 638840887859. The next prime is 638840887921. The reversal of 638840887864 is 468788048836.

638840887864 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 638840887793 and 638840887802.

It is a congruent number.

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, 2111497 + ... + 2395015.

It is an arithmetic number, because the mean of its divisors is an integer number (37968998400).

Almost surely, 2^638840887864 is an apocalyptic number.

It is an amenable number.

638840887864 is a deficient number, since it is larger than the sum of its proper divisors (576167060936).

638840887864 is a wasteful number, since it uses less digits than its factorization.

638840887864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 287563 (or 287559 counting only the distinct ones).

The product of its (nonzero) digits is 396361728, while the sum is 70.

The spelling of 638840887864 in words is "six hundred thirty-eight billion, eight hundred forty million, eight hundred eighty-seven thousand, eight hundred sixty-four".