644663173 has 32 divisors (see below), whose sum is σ = 837347328. Its totient is φ = 481723200.

The previous prime is 644663161. The next prime is 644663203. The reversal of 644663173 is 371366446.

It is a happy number.

644663173 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a de Polignac number, because none of the positive numbers 2^k-644663173 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 (644663473) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 200686 + ... + 203872.

It is an arithmetic number, because the mean of its divisors is an integer number (26167104).

Almost surely, 2^644663173 is an apocalyptic number.

It is an amenable number.

644663173 is a deficient number, since it is larger than the sum of its proper divisors (192684155).

644663173 is a wasteful number, since it uses less digits than its factorization.

644663173 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3313.

The product of its digits is 217728, while the sum is 40.

The square root of 644663173 is about 25390.2180573543. The cubic root of 644663173 is about 863.8618342773.

The spelling of 644663173 in words is "six hundred forty-four million, six hundred sixty-three thousand, one hundred seventy-three".