638922858 has 24 divisors (see below), whose sum is σ = 1486474272. Its totient is φ = 182549304.

The previous prime is 638922857. The next prime is 638922871. The reversal of 638922858 is 858229836.

It is a self number, because there is not a number n which added to its sum of digits gives 638922858.

It is not an unprimeable number, because it can be changed into a prime (638922857) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1086310 + ... + 1086897.

It is an arithmetic number, because the mean of its divisors is an integer number (61936428).

Almost surely, 2^638922858 is an apocalyptic number.

638922858 is an abundant number, since it is smaller than the sum of its proper divisors (847551414).

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

638922858 is a wasteful number, since it uses less digits than its factorization.

638922858 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2173226 (or 2173219 counting only the distinct ones).

The product of its digits is 1658880, while the sum is 51.

The square root of 638922858 is about 25276.9234282972. The cubic root of 638922858 is about 861.2901395105.

The spelling of 638922858 in words is "six hundred thirty-eight million, nine hundred twenty-two thousand, eight hundred fifty-eight".