644404 has 24 divisors (see below), whose sum is σ = 1215200. Its totient is φ = 298080.

The previous prime is 644401. The next prime is 644411. The reversal of 644404 is 404446.

It is a happy number.

644404 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644401) 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, 4567 + ... + 4705.

2⁶⁴⁴⁴⁰⁴ is an apocalyptic number.

It is an amenable number.

644404 is a deficient number, since it is larger than the sum of its proper divisors (570796).

644404 is a wasteful number, since it uses less digits than its factorization.

644404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223 (or 221 counting only the distinct ones).

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

The square root of 644404 is about 802.7477810620. The cubic root of 644404 is about 86.3746053054.

The spelling of 644404 in words is "six hundred forty-four thousand, four hundred four".