644377444 has 24 divisors (see below), whose sum is σ = 1142671320. Its totient is φ = 317915136.

The previous prime is 644377441. The next prime is 644377463. The reversal of 644377444 is 444773446.

It can be written as a sum of positive squares in 4 ways, for example, as 427993344 + 216384100 = 20688^2 + 14710^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 644377444.

It is not an unprimeable number, because it can be changed into a prime (644377441) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 203844 + ... + 206980.

It is an arithmetic number, because the mean of its divisors is an integer number (47611305).

Almost surely, 2^644377444 is an apocalyptic number.

It is an amenable number.

644377444 is a deficient number, since it is larger than the sum of its proper divisors (498293876).

644377444 is a wasteful number, since it uses less digits than its factorization.

644377444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3807 (or 3805 counting only the distinct ones).

The product of its digits is 903168, while the sum is 43.

The square root of 644377444 is about 25384.5906801745. The cubic root of 644377444 is about 863.7341878493.

The spelling of 644377444 in words is "six hundred forty-four million, three hundred seventy-seven thousand, four hundred forty-four".