639606561 has 8 divisors (see below), whose sum is σ = 930336864. Its totient is φ = 387640320.

The previous prime is 639606523. The next prime is 639606577. The reversal of 639606561 is 165606936.

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

It is not a de Polignac number, because 639606561 - 2¹¹ = 639604513 is a prime.

It is not an unprimeable number, because it can be changed into a prime (639606581) 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, 9690976 + ... + 9691041.

It is an arithmetic number, because the mean of its divisors is an integer number (116292108).

Almost surely, 2^639606561 is an apocalyptic number.

It is an amenable number.

639606561 is a deficient number, since it is larger than the sum of its proper divisors (290730303).

639606561 is a wasteful number, since it uses less digits than its factorization.

639606561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19382031.

The product of its (nonzero) digits is 174960, while the sum is 42.

The square root of 639606561 is about 25290.4440649032. Note that the first 3 decimals coincide. The cubic root of 639606561 is about 861.5972484327.

The spelling of 639606561 in words is "six hundred thirty-nine million, six hundred six thousand, five hundred sixty-one".