644332361 has 2 divisors, whose sum is σ = 644332362. Its totient is φ = 644332360.

The previous prime is 644332301. The next prime is 644332363. The reversal of 644332361 is 163233446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 392792761 + 251539600 = 19819^2 + 15860^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644332361 is a prime.

Together with 644332363, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (644332363) 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, 322166180 + 322166181.

It is an arithmetic number, because the mean of its divisors is an integer number (322166181).

Almost surely, 2^644332361 is an apocalyptic number.

It is an amenable number.

644332361 is a deficient number, since it is larger than the sum of its proper divisors (1).

644332361 is an equidigital number, since it uses as much as digits as its factorization.

644332361 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 32.

The square root of 644332361 is about 25383.7026652929. The cubic root of 644332361 is about 863.7140440464.

The spelling of 644332361 in words is "six hundred forty-four million, three hundred thirty-two thousand, three hundred sixty-one".