638117808 has 20 divisors (see below), whose sum is σ = 1648471128. Its totient is φ = 212705920.

The previous prime is 638117801. The next prime is 638117813. The reversal of 638117808 is 808711836.

It is a self number, because there is not a number n which added to its sum of digits gives 638117808.

It is not an unprimeable number, because it can be changed into a prime (638117801) 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 3 ways as a sum of consecutive naturals, for example, 6647013 + ... + 6647108.

Almost surely, 2^638117808 is an apocalyptic number.

It is an amenable number.

638117808 is an abundant number, since it is smaller than the sum of its proper divisors (1010353320).

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

638117808 is a wasteful number, since it uses less digits than its factorization.

638117808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13294132 (or 13294126 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 42.

The square root of 638117808 is about 25260.9938046784. The cubic root of 638117808 is about 860.9282423764.

The spelling of 638117808 in words is "six hundred thirty-eight million, one hundred seventeen thousand, eight hundred eight".