639996838 has 16 divisors (see below), whose sum is σ = 1055839680. Its totient is φ = 289097856.

The previous prime is 639996809. The next prime is 639996871. The reversal of 639996838 is 838699936.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 260643 + ... + 263086.

It is an arithmetic number, because the mean of its divisors is an integer number (65989980).

Almost surely, 2^639996838 is an apocalyptic number.

639996838 is a deficient number, since it is larger than the sum of its proper divisors (415842842).

639996838 is a wasteful number, since it uses less digits than its factorization.

639996838 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 523791.

The product of its digits is 15116544, while the sum is 61.

The square root of 639996838 is about 25298.1587867576. The cubic root of 639996838 is about 861.7724567766.

The spelling of 639996838 in words is "six hundred thirty-nine million, nine hundred ninety-six thousand, eight hundred thirty-eight".