644385 has 48 divisors (see below), whose sum is σ = 1316736. Its totient is φ = 262656.

The previous prime is 644383. The next prime is 644401. The reversal of 644385 is 583446.

It is not a de Polignac number, because 644385 - 2¹ = 644383 is a prime.

644385 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644381) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 33906 + ... + 33924.

It is an arithmetic number, because the mean of its divisors is an integer number (27432).

2⁶⁴⁴³⁸⁵ is an apocalyptic number.

It is an amenable number.

644385 is an abundant number, since it is smaller than the sum of its proper divisors (672351).

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

644385 is a wasteful number, since it uses less digits than its factorization.

644385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70 (or 51 counting only the distinct ones).

The product of its digits is 11520, while the sum is 30.

The square root of 644385 is about 802.7359466225. The cubic root of 644385 is about 86.3737563899.

The spelling of 644385 in words is "six hundred forty-four thousand, three hundred eighty-five".