638725988 has 24 divisors (see below), whose sum is σ = 1131900000. Its totient is φ = 315341568.

The previous prime is 638725987. The next prime is 638725993. The reversal of 638725988 is 889527836.

It is a super-2 number, since 2×638725988² = 815941775493152288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (638725987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 191963 + ... + 195261.

It is an arithmetic number, because the mean of its divisors is an integer number (47162500).

Almost surely, 2^638725988 is an apocalyptic number.

It is an amenable number.

638725988 is a deficient number, since it is larger than the sum of its proper divisors (493174012).

638725988 is a wasteful number, since it uses less digits than its factorization.

638725988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3899 (or 3897 counting only the distinct ones).

The product of its digits is 5806080, while the sum is 56.

The square root of 638725988 is about 25273.0288647799. The cubic root of 638725988 is about 861.2016678971.

The spelling of 638725988 in words is "six hundred thirty-eight million, seven hundred twenty-five thousand, nine hundred eighty-eight".