644323 has 4 divisors (see below), whose sum is σ = 658080. Its totient is φ = 630568.

The previous prime is 644297. The next prime is 644327. The reversal of 644323 is 323446.

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

It is a cyclic number.

It is not a de Polignac number, because 644323 - 2⁵ = 644291 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 644294 and 644303.

It is not an unprimeable number, because it can be changed into a prime (644327) 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 3 ways as a sum of consecutive naturals, for example, 6808 + ... + 6901.

It is an arithmetic number, because the mean of its divisors is an integer number (164520).

2⁶⁴⁴³²³ is an apocalyptic number.

644323 is a deficient number, since it is larger than the sum of its proper divisors (13757).

644323 is a wasteful number, since it uses less digits than its factorization.

644323 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13756.

The product of its digits is 1728, while the sum is 22.

The square root of 644323 is about 802.6973277643. The cubic root of 644323 is about 86.3709861285.

Adding to 644323 its reverse (323446), we get a palindrome (967769).

It can be divided in two parts, 64 and 4323, that multiplied together give a palindrome (276672).

The spelling of 644323 in words is "six hundred forty-four thousand, three hundred twenty-three".