639884066 has 4 divisors (see below), whose sum is σ = 959826102. Its totient is φ = 319942032.

The previous prime is 639884059. The next prime is 639884117. The reversal of 639884066 is 660488936.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 518245225 + 121638841 = 22765^2 + 11029^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159971015 + ... + 159971018.

Almost surely, 2^639884066 is an apocalyptic number.

639884066 is a deficient number, since it is larger than the sum of its proper divisors (319942036).

639884066 is a wasteful number, since it uses less digits than its factorization.

639884066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319942035.

The product of its (nonzero) digits is 1492992, while the sum is 50.

The square root of 639884066 is about 25295.9298307060. The cubic root of 639884066 is about 861.7218369889.

The spelling of 639884066 in words is "six hundred thirty-nine million, eight hundred eighty-four thousand, sixty-six".