664247209 has 2 divisors, whose sum is σ = 664247210. Its totient is φ = 664247208.

The previous prime is 664247197. The next prime is 664247219. The reversal of 664247209 is 902742466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 661261225 + 2985984 = 25715^2 + 1728^2 .

It is a cyclic number.

It is not a de Polignac number, because 664247209 - 2⁹ = 664246697 is a prime.

It is not a weakly prime, because it can be changed into another prime (664247219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332123604 + 332123605.

It is an arithmetic number, because the mean of its divisors is an integer number (332123605).

Almost surely, 2^664247209 is an apocalyptic number.

It is an amenable number.

664247209 is a deficient number, since it is larger than the sum of its proper divisors (1).

664247209 is an equidigital number, since it uses as much as digits as its factorization.

664247209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145152, while the sum is 40.

The square root of 664247209 is about 25772.9937919521. The cubic root of 664247209 is about 872.5223882401.

The spelling of 664247209 in words is "six hundred sixty-four million, two hundred forty-seven thousand, two hundred nine".