644573 has 4 divisors (see below), whose sum is σ = 646620. Its totient is φ = 642528.

The previous prime is 644569. The next prime is 644593. The reversal of 644573 is 375446.

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

It can be written as a sum of positive squares in 2 ways, for example, as 178084 + 466489 = 422^2 + 683^2 .

It is a cyclic number.

It is not a de Polignac number, because 644573 - 2² = 644569 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 (644513) 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, 440 + ... + 1217.

It is an arithmetic number, because the mean of its divisors is an integer number (161655).

2⁶⁴⁴⁵⁷³ is an apocalyptic number.

It is an amenable number.

644573 is a deficient number, since it is larger than the sum of its proper divisors (2047).

644573 is a wasteful number, since it uses less digits than its factorization.

644573 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2046.

The product of its digits is 10080, while the sum is 29.

The square root of 644573 is about 802.8530376102. The cubic root of 644573 is about 86.3821554511.

The spelling of 644573 in words is "six hundred forty-four thousand, five hundred seventy-three".