639694689 has 8 divisors (see below), whose sum is σ = 855652512. Its totient is φ = 425100000.

The previous prime is 639694681. The next prime is 639694691. The reversal of 639694689 is 986496936.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 639694689 - 2³ = 639694681 is a prime.

It is not an unprimeable number, because it can be changed into a prime (639694681) 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, 339687 + ... + 341564.

It is an arithmetic number, because the mean of its divisors is an integer number (106956564).

Almost surely, 2^639694689 is an apocalyptic number.

It is an amenable number.

639694689 is a deficient number, since it is larger than the sum of its proper divisors (215957823).

639694689 is a wasteful number, since it uses less digits than its factorization.

639694689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 681567.

The product of its digits is 15116544, while the sum is 60.

The square root of 639694689 is about 25292.1863230524. The cubic root of 639694689 is about 861.6368182557.

The spelling of 639694689 in words is "six hundred thirty-nine million, six hundred ninety-four thousand, six hundred eighty-nine".