644304440 has 64 divisors (see below), whose sum is σ = 1643392800. Its totient is φ = 225372672.

The previous prime is 644304413. The next prime is 644304443. The reversal of 644304440 is 44403446.

644304440 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×644304440² = 830256422807427200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644304443) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22727 + ... + 42486.

Almost surely, 2^644304440 is an apocalyptic number.

It is an amenable number.

644304440 is an abundant number, since it is smaller than the sum of its proper divisors (999088360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644304440 is a wasteful number, since it uses less digits than its factorization.

644304440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65256 (or 65252 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 29.

The square root of 644304440 is about 25383.1526804690. The cubic root of 644304440 is about 863.7015680275.

Adding to 644304440 its reverse (44403446), we get a palindrome (688707886).

The spelling of 644304440 in words is "six hundred forty-four million, three hundred four thousand, four hundred forty".