639879810838 has 4 divisors (see below), whose sum is σ = 959819716260. Its totient is φ = 319939905418.

The previous prime is 639879810767. The next prime is 639879810863. The reversal of 639879810838 is 838018978936.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159969952708 + ... + 159969952711.

It is an arithmetic number, because the mean of its divisors is an integer number (239954929065).

Almost surely, 2^639879810838 is an apocalyptic number.

639879810838 is a deficient number, since it is larger than the sum of its proper divisors (319939905422).

639879810838 is a wasteful number, since it uses less digits than its factorization.

639879810838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319939905421.

The product of its (nonzero) digits is 125411328, while the sum is 70.

The spelling of 639879810838 in words is "six hundred thirty-nine billion, eight hundred seventy-nine million, eight hundred ten thousand, eight hundred thirty-eight".