644895726916 has 81 divisors (see below), whose sum is σ = 1386015142239. Its totient is φ = 261750632976.

The previous prime is 644895726901. The next prime is 644895726949. The reversal of 644895726916 is 619627598446.

The square root of 644895726916 is 803054.

It is a perfect power (a square), and thus also a powerful number.

644895726916 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 213610855 + ... + 213613873.

Almost surely, 2^644895726916 is an apocalyptic number.

644895726916 is the 803054-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644895726916

644895726916 is an abundant number, since it is smaller than the sum of its proper divisors (741119415323).

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

644895726916 is an equidigital number, since it uses as much as digits as its factorization.

644895726916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6094 (or 3047 counting only the distinct ones).

The product of its digits is 156764160, while the sum is 67.

The spelling of 644895726916 in words is "six hundred forty-four billion, eight hundred ninety-five million, seven hundred twenty-six thousand, nine hundred sixteen".