644264432 has 80 divisors (see below), whose sum is σ = 1460781504. Its totient is φ = 269568000.

The previous prime is 644264417. The next prime is 644264443. The reversal of 644264432 is 234462446.

644264432 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 644264392 and 644264401.

It is a congruent number.

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, 1236332 + ... + 1236852.

Almost surely, 2^644264432 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 644264432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (730390752).

644264432 is an abundant number, since it is smaller than the sum of its proper divisors (816517072).

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

644264432 is a wasteful number, since it uses less digits than its factorization.

644264432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 778 (or 772 counting only the distinct ones).

The product of its digits is 110592, while the sum is 35.

The square root of 644264432 is about 25382.3645864604. The cubic root of 644264432 is about 863.6836905121.

The spelling of 644264432 in words is "six hundred forty-four million, two hundred sixty-four thousand, four hundred thirty-two".