644008 has 16 divisors (see below), whose sum is σ = 1224000. Its totient is φ = 317616.

The previous prime is 643991. The next prime is 644009. The reversal of 644008 is 800446.

644008 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 644008.

It is not an unprimeable number, because it can be changed into a prime (644009) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 123 + ... + 1141.

It is an arithmetic number, because the mean of its divisors is an integer number (76500).

2⁶⁴⁴⁰⁰⁸ is an apocalyptic number.

It is an amenable number.

644008 is a deficient number, since it is larger than the sum of its proper divisors (579992).

644008 is a wasteful number, since it uses less digits than its factorization.

644008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1104 (or 1100 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 644008 is about 802.5010903419. The cubic root of 644008 is about 86.3569086676.

The spelling of 644008 in words is "six hundred forty-four thousand, eight".