638756172 has 24 divisors (see below), whose sum is σ = 1656034800. Its totient is φ = 212918688.

The previous prime is 638756171. The next prime is 638756177. The reversal of 638756172 is 271657836.

638756172 is a `hidden beast` number, since 6 + 3 + 87 + 561 + 7 + 2 = 666.

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 not an unprimeable number, because it can be changed into a prime (638756171) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2957097 + ... + 2957312.

It is an arithmetic number, because the mean of its divisors is an integer number (69001450).

Almost surely, 2^638756172 is an apocalyptic number.

It is an amenable number.

638756172 is an abundant number, since it is smaller than the sum of its proper divisors (1017278628).

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

638756172 is a wasteful number, since it uses less digits than its factorization.

638756172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5914422 (or 5914414 counting only the distinct ones).

The product of its digits is 423360, while the sum is 45.

The square root of 638756172 is about 25273.6260160666. The cubic root of 638756172 is about 861.2152334960.

The spelling of 638756172 in words is "six hundred thirty-eight million, seven hundred fifty-six thousand, one hundred seventy-two".