639861842 has 16 divisors (see below), whose sum is σ = 966822912. Its totient is φ = 317594880.

The previous prime is 639861839. The next prime is 639861883. The reversal of 639861842 is 248168936.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 218963 + ... + 221865.

It is an arithmetic number, because the mean of its divisors is an integer number (60426432).

Almost surely, 2^639861842 is an apocalyptic number.

639861842 is a deficient number, since it is larger than the sum of its proper divisors (326961070).

639861842 is a wasteful number, since it uses less digits than its factorization.

639861842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3673.

The product of its digits is 497664, while the sum is 47.

The square root of 639861842 is about 25295.4905467358. The cubic root of 639861842 is about 861.7118606359.

The spelling of 639861842 in words is "six hundred thirty-nine million, eight hundred sixty-one thousand, eight hundred forty-two".