644325361 has 4 divisors (see below), whose sum is σ = 644410852. Its totient is φ = 644239872.

The previous prime is 644325329. The next prime is 644325391. The reversal of 644325361 is 163523446.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 535644736 + 108680625 = 23144^2 + 10425^2 .

It is a cyclic number.

It is not a de Polignac number, because 644325361 - 2⁵ = 644325329 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644325391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30216 + ... + 46921.

It is an arithmetic number, because the mean of its divisors is an integer number (161102713).

Almost surely, 2^644325361 is an apocalyptic number.

It is an amenable number.

644325361 is a deficient number, since it is larger than the sum of its proper divisors (85491).

644325361 is an equidigital number, since it uses as much as digits as its factorization.

644325361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85490.

The product of its digits is 51840, while the sum is 34.

The square root of 644325361 is about 25383.5647811729. The cubic root of 644325361 is about 863.7109162506.

The spelling of 644325361 in words is "six hundred forty-four million, three hundred twenty-five thousand, three hundred sixty-one".