638407405756 has 12 divisors (see below), whose sum is σ = 1121188808880. Its totient is φ = 318067746080.

The previous prime is 638407405693. The next prime is 638407405777. The reversal of 638407405756 is 657504704836.

It is a junction number, because it is equal to n+sod(n) for n = 638407405697 and 638407405706.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 283987936 + ... + 283990183.

It is an arithmetic number, because the mean of its divisors is an integer number (93432400740).

Almost surely, 2^638407405756 is an apocalyptic number.

It is an amenable number.

638407405756 is a deficient number, since it is larger than the sum of its proper divisors (482781403124).

638407405756 is a wasteful number, since it uses less digits than its factorization.

638407405756 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 567978404 (or 567978402 counting only the distinct ones).

The product of its (nonzero) digits is 16934400, while the sum is 55.

The spelling of 638407405756 in words is "six hundred thirty-eight billion, four hundred seven million, four hundred five thousand, seven hundred fifty-six".