639699478 has 16 divisors (see below), whose sum is σ = 1049214096. Its totient is φ = 290096640.

The previous prime is 639699457. The next prime is 639699479. The reversal of 639699478 is 874996936.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639699479) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24051 + ... + 43102.

It is an arithmetic number, because the mean of its divisors is an integer number (65575881).

Almost surely, 2^639699478 is an apocalyptic number.

639699478 is a deficient number, since it is larger than the sum of its proper divisors (409514618).

639699478 is a wasteful number, since it uses less digits than its factorization.

639699478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67599.

The product of its digits is 17635968, while the sum is 61.

The square root of 639699478 is about 25292.2809963831. The cubic root of 639699478 is about 861.6389684317.

The spelling of 639699478 in words is "six hundred thirty-nine million, six hundred ninety-nine thousand, four hundred seventy-eight".