664655609 has 2 divisors, whose sum is σ = 664655610. Its totient is φ = 664655608.

The previous prime is 664655599. The next prime is 664655627. The reversal of 664655609 is 906556466.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 510895609 + 153760000 = 22603^2 + 12400^2 .

It is a cyclic number.

It is not a de Polignac number, because 664655609 - 2¹² = 664651513 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (664655639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332327804 + 332327805.

It is an arithmetic number, because the mean of its divisors is an integer number (332327805).

Almost surely, 2^664655609 is an apocalyptic number.

It is an amenable number.

664655609 is a deficient number, since it is larger than the sum of its proper divisors (1).

664655609 is an equidigital number, since it uses as much as digits as its factorization.

664655609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1166400, while the sum is 47.

The square root of 664655609 is about 25780.9155966191. The cubic root of 664655609 is about 872.7011696406.

The spelling of 664655609 in words is "six hundred sixty-four million, six hundred fifty-five thousand, six hundred nine".