638968858 has 16 divisors (see below), whose sum is σ = 1048329216. Its totient is φ = 289678240.

The previous prime is 638968849. The next prime is 638968859. The reversal of 638968858 is 858869836.

It is a junction number, because it is equal to n+sod(n) for n = 638968796 and 638968805.

It is not an unprimeable number, because it can be changed into a prime (638968859) 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 7 ways as a sum of consecutive naturals, for example, 29491 + ... + 46342.

It is an arithmetic number, because the mean of its divisors is an integer number (65520576).

Almost surely, 2^638968858 is an apocalyptic number.

638968858 is a deficient number, since it is larger than the sum of its proper divisors (409360358).

638968858 is a wasteful number, since it uses less digits than its factorization.

638968858 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76229.

The product of its digits is 19906560, while the sum is 61.

The square root of 638968858 is about 25277.8333327839. The cubic root of 638968858 is about 861.3108088788.

The spelling of 638968858 in words is "six hundred thirty-eight million, nine hundred sixty-eight thousand, eight hundred fifty-eight".