644173 has 2 divisors, whose sum is σ = 644174. Its totient is φ = 644172.

The previous prime is 644159. The next prime is 644191. The reversal of 644173 is 371446.

644173 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 328329 + 315844 = 573^2 + 562^2 .

It is a cyclic number.

It is not a de Polignac number, because 644173 - 2⁵ = 644141 is a prime.

It is equal to p₅₂₃₇₈ and since 644173 and 52378 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322086 + 322087.

It is an arithmetic number, because the mean of its divisors is an integer number (322087).

2⁶⁴⁴¹⁷³ is an apocalyptic number.

It is an amenable number.

644173 is a deficient number, since it is larger than the sum of its proper divisors (1).

644173 is an equidigital number, since it uses as much as digits as its factorization.

644173 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2016, while the sum is 25.

The square root of 644173 is about 802.6038873566. The cubic root of 644173 is about 86.3642831480.

The spelling of 644173 in words is "six hundred forty-four thousand, one hundred seventy-three".