664544509 has 2 divisors, whose sum is σ = 664544510. Its totient is φ = 664544508.

The previous prime is 664544473. The next prime is 664544521. The reversal of 664544509 is 905445466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 594872100 + 69672409 = 24390^2 + 8347^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664544509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664544539) 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, 332272254 + 332272255.

It is an arithmetic number, because the mean of its divisors is an integer number (332272255).

Almost surely, 2^664544509 is an apocalyptic number.

It is an amenable number.

664544509 is a deficient number, since it is larger than the sum of its proper divisors (1).

664544509 is an equidigital number, since it uses as much as digits as its factorization.

664544509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 518400, while the sum is 43.

The square root of 664544509 is about 25778.7608119553. The cubic root of 664544509 is about 872.6525416989.

The spelling of 664544509 in words is "six hundred sixty-four million, five hundred forty-four thousand, five hundred nine".