639128704 has 32 divisors (see below), whose sum is σ = 1279031040. Its totient is φ = 318117120.

The previous prime is 639128689. The next prime is 639128731. The reversal of 639128704 is 407821936.

It is a tau number, because it is divible by the number of its divisors (32).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17349 + ... + 39739.

It is an arithmetic number, because the mean of its divisors is an integer number (39969720).

Almost surely, 2^639128704 is an apocalyptic number.

639128704 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639128704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (639515520).

639128704 is an abundant number, since it is smaller than the sum of its proper divisors (639902336).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

639128704 is a wasteful number, since it uses less digits than its factorization.

639128704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22628 (or 22616 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 40.

The square root of 639128704 is about 25280.9949171309. The cubic root of 639128704 is about 861.3826254246.

The spelling of 639128704 in words is "six hundred thirty-nine million, one hundred twenty-eight thousand, seven hundred four".