644024 has 24 divisors (see below), whose sum is σ = 1280160. Its totient is φ = 303696.

The previous prime is 644009. The next prime is 644029. The reversal of 644024 is 420446.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 643987 and 644005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644029) 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 5 ways as a sum of consecutive naturals, for example, 2777 + ... + 2999.

It is an arithmetic number, because the mean of its divisors is an integer number (53340).

2⁶⁴⁴⁰²⁴ is an apocalyptic number.

It is an amenable number.

644024 is a deficient number, since it is larger than the sum of its proper divisors (636136).

644024 is a wasteful number, since it uses less digits than its factorization.

644024 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267 (or 244 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 644024 is about 802.5110591138. The cubic root of 644024 is about 86.3576238238.

The spelling of 644024 in words is "six hundred forty-four thousand, twenty-four".