644304432 has 80 divisors (see below), whose sum is σ = 1724139648. Its totient is φ = 207191040.

The previous prime is 644304413. The next prime is 644304443. The reversal of 644304432 is 234403446.

It is a self number, because there is not a number n which added to its sum of digits gives 644304432.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 169432 + ... + 173192.

Almost surely, 2^644304432 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644304432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (862069824).

644304432 is an abundant number, since it is smaller than the sum of its proper divisors (1079835216).

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

644304432 is a wasteful number, since it uses less digits than its factorization.

644304432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3898 (or 3892 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 30.

The square root of 644304432 is about 25383.1525228842. The cubic root of 644304432 is about 863.7015644528.

Adding to 644304432 its reverse (234403446), we get a palindrome (878707878).

The spelling of 644304432 in words is "six hundred forty-four million, three hundred four thousand, four hundred thirty-two".