644056513 has 2 divisors, whose sum is σ = 644056514. Its totient is φ = 644056512.

The previous prime is 644056507. The next prime is 644056529. The reversal of 644056513 is 315650446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 618168769 + 25887744 = 24863^2 + 5088^2 .

It is a cyclic number.

It is not a de Polignac number, because 644056513 - 2⁹ = 644056001 is a prime.

It is not a weakly prime, because it can be changed into another prime (644056313) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322028256 + 322028257.

It is an arithmetic number, because the mean of its divisors is an integer number (322028257).

Almost surely, 2^644056513 is an apocalyptic number.

It is an amenable number.

644056513 is a deficient number, since it is larger than the sum of its proper divisors (1).

644056513 is an equidigital number, since it uses as much as digits as its factorization.

644056513 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 43200, while the sum is 34.

The square root of 644056513 is about 25378.2685185574. The cubic root of 644056513 is about 863.5907702962.

The spelling of 644056513 in words is "six hundred forty-four million, fifty-six thousand, five hundred thirteen".