638657972 has 24 divisors (see below), whose sum is σ = 1184875776. Its totient is φ = 300169088.

The previous prime is 638657959. The next prime is 638658029. The reversal of 638657972 is 279756836.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 53243 + ... + 64125.

It is an arithmetic number, because the mean of its divisors is an integer number (49369824).

Almost surely, 2^638657972 is an apocalyptic number.

It is an amenable number.

638657972 is a deficient number, since it is larger than the sum of its proper divisors (546217804).

638657972 is a wasteful number, since it uses less digits than its factorization.

638657972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11767 (or 11765 counting only the distinct ones).

The product of its digits is 3810240, while the sum is 53.

The square root of 638657972 is about 25271.6832047254. The cubic root of 638657972 is about 861.1710978910.

The spelling of 638657972 in words is "six hundred thirty-eight million, six hundred fifty-seven thousand, nine hundred seventy-two".