644081173 has 4 divisors (see below), whose sum is σ = 644245920. Its totient is φ = 643916428.

The previous prime is 644081161. The next prime is 644081183. The reversal of 644081173 is 371180446.

It is a happy number.

644081173 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 a cyclic number.

It is not a de Polignac number, because 644081173 - 2²⁹ = 107210261 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 (644081143) 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, 76363 + ... + 84376.

It is an arithmetic number, because the mean of its divisors is an integer number (161061480).

Almost surely, 2^644081173 is an apocalyptic number.

It is an amenable number.

644081173 is a deficient number, since it is larger than the sum of its proper divisors (164747).

644081173 is a wasteful number, since it uses less digits than its factorization.

644081173 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164746.

The product of its (nonzero) digits is 16128, while the sum is 34.

The square root of 644081173 is about 25378.7543626554. The cubic root of 644081173 is about 863.6017920394.

The spelling of 644081173 in words is "six hundred forty-four million, eighty-one thousand, one hundred seventy-three".