644733394 has 16 divisors (see below), whose sum is σ = 1002660120. Its totient is φ = 310562560.

The previous prime is 644733389. The next prime is 644733413. The reversal of 644733394 is 493337446.

It can be written as a sum of positive squares in 4 ways, for example, as 552861169 + 91872225 = 23513^2 + 9585^2 .

It is a super-2 number, since 2×644733394² = 831362298677518472, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 644733394.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14682 + ... + 38794.

Almost surely, 2^644733394 is an apocalyptic number.

644733394 is a deficient number, since it is larger than the sum of its proper divisors (357926726).

644733394 is a wasteful number, since it uses less digits than its factorization.

644733394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24605.

The product of its digits is 653184, while the sum is 43.

The square root of 644733394 is about 25391.6008554010. The cubic root of 644733394 is about 863.8931989971.

The spelling of 644733394 in words is "six hundred forty-four million, seven hundred thirty-three thousand, three hundred ninety-four".