639822394 has 4 divisors (see below), whose sum is σ = 959733594. Its totient is φ = 319911196.

The previous prime is 639822383. The next prime is 639822401. The reversal of 639822394 is 493228936.

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., 636805225 + 3017169 = 25235^2 + 1737^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159955597 + ... + 159955600.

Almost surely, 2^639822394 is an apocalyptic number.

639822394 is a deficient number, since it is larger than the sum of its proper divisors (319911200).

639822394 is a wasteful number, since it uses less digits than its factorization.

639822394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319911199.

The product of its digits is 559872, while the sum is 46.

The square root of 639822394 is about 25294.7107909934. The cubic root of 639822394 is about 861.6941518610.

The spelling of 639822394 in words is "six hundred thirty-nine million, eight hundred twenty-two thousand, three hundred ninety-four".