638910738 has 24 divisors (see below), whose sum is σ = 1389703068. Its totient is φ = 212140032.

The previous prime is 638910703. The next prime is 638910757. The reversal of 638910738 is 837019836.

It is a happy number.

638910738 is a `hidden beast` number, since 638 + 9 + 1 + 0 + 7 + 3 + 8 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 597655809 + 41254929 = 24447^2 + 6423^2 .

It is a super-2 number, since 2×638910738² = 816413862263409288, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 638910693 and 638910702.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 64431 + ... + 73682.

Almost surely, 2^638910738 is an apocalyptic number.

638910738 is an abundant number, since it is smaller than the sum of its proper divisors (750792330).

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

638910738 is a wasteful number, since it uses less digits than its factorization.

638910738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138378 (or 138375 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 45.

The square root of 638910738 is about 25276.6836827935. The cubic root of 638910738 is about 861.2846934162.

The spelling of 638910738 in words is "six hundred thirty-eight million, nine hundred ten thousand, seven hundred thirty-eight".