639656834 has 4 divisors (see below), whose sum is σ = 959485254. Its totient is φ = 319828416.

The previous prime is 639656791. The next prime is 639656837. The reversal of 639656834 is 438656936.

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., 522259609 + 117397225 = 22853^2 + 10835^2 .

It is not an unprimeable number, because it can be changed into a prime (639656837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159914207 + ... + 159914210.

Almost surely, 2^639656834 is an apocalyptic number.

639656834 is a deficient number, since it is larger than the sum of its proper divisors (319828420).

639656834 is a wasteful number, since it uses less digits than its factorization.

639656834 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319828419.

The product of its digits is 2799360, while the sum is 50.

The square root of 639656834 is about 25291.4379583289. The cubic root of 639656834 is about 861.6198216552.

The spelling of 639656834 in words is "six hundred thirty-nine million, six hundred fifty-six thousand, eight hundred thirty-four".