644350013 has 2 divisors, whose sum is σ = 644350014. Its totient is φ = 644350012.

The previous prime is 644350009. The next prime is 644350027. The reversal of 644350013 is 310053446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 331130809 + 313219204 = 18197^2 + 17698^2 .

It is a cyclic number.

It is not a de Polignac number, because 644350013 - 2² = 644350009 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644350513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322175006 + 322175007.

It is an arithmetic number, because the mean of its divisors is an integer number (322175007).

Almost surely, 2^644350013 is an apocalyptic number.

It is an amenable number.

644350013 is a deficient number, since it is larger than the sum of its proper divisors (1).

644350013 is an equidigital number, since it uses as much as digits as its factorization.

644350013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 26.

The square root of 644350013 is about 25384.0503663226. The cubic root of 644350013 is about 863.7219313533.

The spelling of 644350013 in words is "six hundred forty-four million, three hundred fifty thousand, thirteen".