639831538 has 16 divisors (see below), whose sum is σ = 977326560. Its totient is φ = 314109376.

The previous prime is 639831487. The next prime is 639831557. The reversal of 639831538 is 835138936.

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, 10953 + ... + 37411.

It is an arithmetic number, because the mean of its divisors is an integer number (61082910).

Almost surely, 2^639831538 is an apocalyptic number.

639831538 is a deficient number, since it is larger than the sum of its proper divisors (337495022).

639831538 is a wasteful number, since it uses less digits than its factorization.

639831538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26681.

The product of its digits is 466560, while the sum is 46.

The square root of 639831538 is about 25294.8915395975. The cubic root of 639831538 is about 861.6982567990.

The spelling of 639831538 in words is "six hundred thirty-nine million, eight hundred thirty-one thousand, five hundred thirty-eight".