638699388 has 12 divisors (see below), whose sum is σ = 1490298600. Its totient is φ = 212899792.

The previous prime is 638699329. The next prime is 638699407. The reversal of 638699388 is 883996836.

638699388 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26612463 + ... + 26612486.

It is an arithmetic number, because the mean of its divisors is an integer number (124191550).

Almost surely, 2^638699388 is an apocalyptic number.

It is an amenable number.

638699388 is an abundant number, since it is smaller than the sum of its proper divisors (851599212).

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

638699388 is a wasteful number, since it uses less digits than its factorization.

638699388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53224956 (or 53224954 counting only the distinct ones).

The product of its digits is 13436928, while the sum is 60.

The square root of 638699388 is about 25272.5026065881. The cubic root of 638699388 is about 861.1897127014.

The spelling of 638699388 in words is "six hundred thirty-eight million, six hundred ninety-nine thousand, three hundred eighty-eight".