644604 has 12 divisors (see below), whose sum is σ = 1504104. Its totient is φ = 214864.

The previous prime is 644599. The next prime is 644617. The reversal of 644604 is 406446.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26847 + ... + 26870.

It is an arithmetic number, because the mean of its divisors is an integer number (125342).

2⁶⁴⁴⁶⁰⁴ is an apocalyptic number.

It is an amenable number.

644604 is an abundant number, since it is smaller than the sum of its proper divisors (859500).

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

644604 is a wasteful number, since it uses less digits than its factorization.

644604 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53724 (or 53722 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 24.

The square root of 644604 is about 802.8723435267. The cubic root of 644604 is about 86.3835402459.

The spelling of 644604 in words is "six hundred forty-four thousand, six hundred four".