644601173 has 2 divisors, whose sum is σ = 644601174. Its totient is φ = 644601172.

The previous prime is 644601149. The next prime is 644601179. The reversal of 644601173 is 371106446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 631366129 + 13235044 = 25127^2 + 3638^2 .

It is a cyclic number.

It is not a de Polignac number, because 644601173 - 2⁶ = 644601109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644601179) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322300586 + 322300587.

It is an arithmetic number, because the mean of its divisors is an integer number (322300587).

Almost surely, 2^644601173 is an apocalyptic number.

It is an amenable number.

644601173 is a deficient number, since it is larger than the sum of its proper divisors (1).

644601173 is an equidigital number, since it uses as much as digits as its factorization.

644601173 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12096, while the sum is 32.

The square root of 644601173 is about 25388.9970853518. The cubic root of 644601173 is about 863.8341396335.

The spelling of 644601173 in words is "six hundred forty-four million, six hundred one thousand, one hundred seventy-three".