644438 has 16 divisors (see below), whose sum is σ = 1028160. Its totient is φ = 302400.

The previous prime is 644431. The next prime is 644443. The reversal of 644438 is 834446.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 644438.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644431) 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 7 ways as a sum of consecutive naturals, for example, 2243 + ... + 2513.

It is an arithmetic number, because the mean of its divisors is an integer number (64260).

2⁶⁴⁴⁴³⁸ is an apocalyptic number.

644438 is a deficient number, since it is larger than the sum of its proper divisors (383722).

644438 is a wasteful number, since it uses less digits than its factorization.

644438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 343.

The product of its digits is 9216, while the sum is 29.

The square root of 644438 is about 802.7689580446. The cubic root of 644438 is about 86.3761243757.

644438 divided by its sum of digits (29) gives a palindrome (22222).

It can be divided in two parts, 6 and 44438, that added together give a palindrome (44444).

The spelling of 644438 in words is "six hundred forty-four thousand, four hundred thirty-eight".