638971388 has 48 divisors (see below), whose sum is σ = 1255177728. Its totient is φ = 282096000.

The previous prime is 638971369. The next prime is 638971391. The reversal of 638971388 is 883179836.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 488231 + ... + 489537.

It is an arithmetic number, because the mean of its divisors is an integer number (26149536).

Almost surely, 2^638971388 is an apocalyptic number.

It is an amenable number.

638971388 is a deficient number, since it is larger than the sum of its proper divisors (616206340).

638971388 is a wasteful number, since it uses less digits than its factorization.

638971388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1634 (or 1632 counting only the distinct ones).

The product of its digits is 1741824, while the sum is 53.

The square root of 638971388 is about 25277.8833765804. The cubic root of 638971388 is about 861.3119456653.

It can be divided in two parts, 6389 and 71388, that added together give a palindrome (77777).

The spelling of 638971388 in words is "six hundred thirty-eight million, nine hundred seventy-one thousand, three hundred eighty-eight".