638816256 has 312 divisors, whose sum is σ = 2098992896. Its totient is φ = 185794560.

The previous prime is 638816239. The next prime is 638816291. The reversal of 638816256 is 652618836.

638816256 is a `hidden beast` number, since 6 + 388 + 16 + 256 = 666.

It is a tau number, because it is divible by the number of its divisors (312).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14856171 + ... + 14856213.

Almost surely, 2^638816256 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638816256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1049496448).

638816256 is an abundant number, since it is smaller than the sum of its proper divisors (1460176640).

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

638816256 is a wasteful number, since it uses less digits than its factorization.

638816256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117 (or 92 counting only the distinct ones).

The product of its digits is 414720, while the sum is 45.

The square root of 638816256 is about 25274.8146580742. The cubic root of 638816256 is about 861.2422357836.

The spelling of 638816256 in words is "six hundred thirty-eight million, eight hundred sixteen thousand, two hundred fifty-six".