638817992 has 16 divisors (see below), whose sum is σ = 1236422400. Its totient is φ = 309105360.

The previous prime is 638817967. The next prime is 638818009. The reversal of 638817992 is 299718836.

It is a Smith number, since the sum of its digits (53) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

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, 1287692 + ... + 1288187.

It is an arithmetic number, because the mean of its divisors is an integer number (77276400).

Almost surely, 2^638817992 is an apocalyptic number.

638817992 is a gapful number since it is divisible by the number (62) formed by its first and last digit.

It is an amenable number.

638817992 is a deficient number, since it is larger than the sum of its proper divisors (597604408).

638817992 is a wasteful number, since it uses less digits than its factorization.

638817992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2575916 (or 2575912 counting only the distinct ones).

The product of its digits is 1306368, while the sum is 53.

The square root of 638817992 is about 25274.8490005381. The cubic root of 638817992 is about 861.2430159324.

The spelling of 638817992 in words is "six hundred thirty-eight million, eight hundred seventeen thousand, nine hundred ninety-two".