644223 has 4 divisors (see below), whose sum is σ = 858968. Its totient is φ = 429480.

The previous prime is 644201. The next prime is 644227. The reversal of 644223 is 322446.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 644223 - 2⁵ = 644191 is a prime.

It is a D-number.

It is a Duffinian number.

644223 is a lucky number.

It is a plaindrome in base 14.

It is a self number, because there is not a number n which added to its sum of digits gives 644223.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107368 + ... + 107373.

It is an arithmetic number, because the mean of its divisors is an integer number (214742).

2⁶⁴⁴²²³ is an apocalyptic number.

644223 is a deficient number, since it is larger than the sum of its proper divisors (214745).

644223 is a wasteful number, since it uses less digits than its factorization.

644223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214744.

The product of its digits is 1152, while the sum is 21.

The square root of 644223 is about 802.6350353679. The cubic root of 644223 is about 86.3665175904.

Adding to 644223 its reverse (322446), we get a palindrome (966669).

The spelling of 644223 in words is "six hundred forty-four thousand, two hundred twenty-three".