638667657634920 has 64 divisors (see below), whose sum is σ = 1917805421992320. Its totient is φ = 170151157672704.

The previous prime is 638667657634907. The next prime is 638667657634957. The reversal of 638667657634920 is 29436756766836.

638667657634920 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2503273419 + ... + 2503528538.

It is an arithmetic number, because the mean of its divisors is an integer number (29965709718630).

Almost surely, 2^{638667657634920} is an apocalyptic number.

638667657634920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

638667657634920 is an abundant number, since it is smaller than the sum of its proper divisors (1279137764357400).

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

638667657634920 is a wasteful number, since it uses less digits than its factorization.

638667657634920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5006803034 (or 5006803030 counting only the distinct ones).

The product of its (nonzero) digits is 9876142080, while the sum is 78.

The spelling of 638667657634920 in words is "six hundred thirty-eight trillion, six hundred sixty-seven billion, six hundred fifty-seven million, six hundred thirty-four thousand, nine hundred twenty".