644245 has 16 divisors (see below), whose sum is σ = 898560. Its totient is φ = 434304.

The previous prime is 644239. The next prime is 644257. The reversal of 644245 is 542446.

644245 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 644245 - 2⁷ = 644117 is a prime.

644245 is a lucky number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2649 + ... + 2881.

It is an arithmetic number, because the mean of its divisors is an integer number (56160).

2⁶⁴⁴²⁴⁵ is an apocalyptic number.

It is an amenable number.

644245 is a deficient number, since it is larger than the sum of its proper divisors (254315).

644245 is a wasteful number, since it uses less digits than its factorization.

644245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 324.

The product of its digits is 3840, while the sum is 25.

The square root of 644245 is about 802.6487401099. The cubic root of 644245 is about 86.3675007085.

The spelling of 644245 in words is "six hundred forty-four thousand, two hundred forty-five".