644044 has 12 divisors (see below), whose sum is σ = 1146600. Its totient is φ = 316448.

The previous prime is 644029. The next prime is 644047. The reversal of 644044 is 440446.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (644047) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1129 + ... + 1600.

It is an arithmetic number, because the mean of its divisors is an integer number (95550).

2⁶⁴⁴⁰⁴⁴ is an apocalyptic number.

It is an amenable number.

644044 is a deficient number, since it is larger than the sum of its proper divisors (502556).

644044 is a wasteful number, since it uses less digits than its factorization.

644044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2792 (or 2790 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 22.

The square root of 644044 is about 802.5235199046. The cubic root of 644044 is about 86.3585177525.

The spelling of 644044 in words is "six hundred forty-four thousand, forty-four".