644940912 has 160 divisors (see below), whose sum is σ = 2089580544. Its totient is φ = 166521600.

The previous prime is 644940899. The next prime is 644940929. The reversal of 644940912 is 219049446.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 779443 + ... + 780269.

Almost surely, 2^644940912 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 644940912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1044790272).

644940912 is an abundant number, since it is smaller than the sum of its proper divisors (1444639632).

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

644940912 is a wasteful number, since it uses less digits than its factorization.

644940912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1067 (or 1061 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 39.

The square root of 644940912 is about 25395.6868778933. The cubic root of 644940912 is about 863.9858751120.

The spelling of 644940912 in words is "six hundred forty-four million, nine hundred forty thousand, nine hundred twelve".