644673 has 4 divisors (see below), whose sum is σ = 859568. Its totient is φ = 429780.

The previous prime is 644671. The next prime is 644687. The reversal of 644673 is 376446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 644673 - 2¹ = 644671 is a prime.

It is a D-number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644673.

It is not an unprimeable number, because it can be changed into a prime (644671) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107443 + ... + 107448.

It is an arithmetic number, because the mean of its divisors is an integer number (214892).

2⁶⁴⁴⁶⁷³ is an apocalyptic number.

It is an amenable number.

644673 is a deficient number, since it is larger than the sum of its proper divisors (214895).

644673 is a wasteful number, since it uses less digits than its factorization.

644673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214894.

The product of its digits is 12096, while the sum is 30.

The square root of 644673 is about 802.9153130935. The cubic root of 644673 is about 86.3866223715.

The spelling of 644673 in words is "six hundred forty-four thousand, six hundred seventy-three".