638625856 has 28 divisors (see below), whose sum is σ = 1382481360. Its totient is φ = 290284160.

The previous prime is 638625851. The next prime is 638625857. The reversal of 638625856 is 658526836.

It is not an unprimeable number, because it can be changed into a prime (638625851) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 452866 + ... + 454273.

Almost surely, 2^638625856 is an apocalyptic number.

It is an amenable number.

638625856 is an abundant number, since it is smaller than the sum of its proper divisors (743855504).

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

638625856 is a wasteful number, since it uses less digits than its factorization.

638625856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 907162 (or 907152 counting only the distinct ones).

The product of its digits is 2073600, while the sum is 49.

The square root of 638625856 is about 25271.0477819975. The cubic root of 638625856 is about 861.1566624990.

The spelling of 638625856 in words is "six hundred thirty-eight million, six hundred twenty-five thousand, eight hundred fifty-six".