644259 has 16 divisors (see below), whose sum is σ = 1071360. Its totient is φ = 334560.

The previous prime is 644257. The next prime is 644261. The reversal of 644259 is 952446.

644259 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (644257) and next prime (644261).

It is not a de Polignac number, because 644259 - 2¹ = 644257 is a prime.

It is a nialpdrome in base 7.

It is not an unprimeable number, because it can be changed into a prime (644257) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1164 + ... + 1625.

It is an arithmetic number, because the mean of its divisors is an integer number (66960).

2⁶⁴⁴²⁵⁹ is an apocalyptic number.

644259 is a deficient number, since it is larger than the sum of its proper divisors (427101).

644259 is a wasteful number, since it uses less digits than its factorization.

644259 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2810.

The product of its digits is 8640, while the sum is 30.

The square root of 644259 is about 802.6574611875. The cubic root of 644259 is about 86.3681263174.

It can be divided in two parts, 644 and 259, that added together give a triangular number (903 = T₄₂).

The spelling of 644259 in words is "six hundred forty-four thousand, two hundred fifty-nine".