644423 has 8 divisors (see below), whose sum is σ = 730800. Its totient is φ = 563328.

The previous prime is 644411. The next prime is 644431. The reversal of 644423 is 324446.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644423 - 2⁶ = 644359 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644443) 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, 1058 + ... + 1551.

It is an arithmetic number, because the mean of its divisors is an integer number (91350).

2⁶⁴⁴⁴²³ is an apocalyptic number.

644423 is a deficient number, since it is larger than the sum of its proper divisors (86377).

644423 is a wasteful number, since it uses less digits than its factorization.

644423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2641.

The product of its digits is 2304, while the sum is 23.

The square root of 644423 is about 802.7596153270. The cubic root of 644423 is about 86.3754542042.

Adding to 644423 its sum of digits (23), we get a palindrome (644446).

Adding to 644423 its reverse (324446), we get a palindrome (968869).

The spelling of 644423 in words is "six hundred forty-four thousand, four hundred twenty-three".