644646394 has 16 divisors (see below), whose sum is σ = 1143216000. Its totient is φ = 266750064.

The previous prime is 644646361. The next prime is 644646413. The reversal of 644646394 is 493646446.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 793494 + ... + 794305.

It is an arithmetic number, because the mean of its divisors is an integer number (71451000).

Almost surely, 2^644646394 is an apocalyptic number.

644646394 is a deficient number, since it is larger than the sum of its proper divisors (498569606).

644646394 is a wasteful number, since it uses less digits than its factorization.

644646394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1587837.

The product of its digits is 1492992, while the sum is 46.

The square root of 644646394 is about 25389.8876326777. The cubic root of 644646394 is about 863.8543394779.

The spelling of 644646394 in words is "six hundred forty-four million, six hundred forty-six thousand, three hundred ninety-four".