639079521 has 8 divisors (see below), whose sum is σ = 902229984. Its totient is φ = 400991040.

The previous prime is 639079501. The next prime is 639079603. The reversal of 639079521 is 125970936.

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

It is not a de Polignac number, because 639079521 - 2⁵ = 639079489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (639079501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6265435 + ... + 6265536.

It is an arithmetic number, because the mean of its divisors is an integer number (112778748).

Almost surely, 2^639079521 is an apocalyptic number.

It is an amenable number.

639079521 is a deficient number, since it is larger than the sum of its proper divisors (263150463).

639079521 is a wasteful number, since it uses less digits than its factorization.

639079521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12530991.

The product of its (nonzero) digits is 102060, while the sum is 42.

The square root of 639079521 is about 25280.0221716675. The cubic root of 639079521 is about 861.3605294741.

The spelling of 639079521 in words is "six hundred thirty-nine million, seventy-nine thousand, five hundred twenty-one".