664043609 has 2 divisors, whose sum is σ = 664043610. Its totient is φ = 664043608.

The previous prime is 664043573. The next prime is 664043623. The reversal of 664043609 is 906340466.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 386987584 + 277056025 = 19672^2 + 16645^2 .

It is a cyclic number.

It is not a de Polignac number, because 664043609 - 2⁸ = 664043353 is a prime.

It is not a weakly prime, because it can be changed into another prime (664043629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332021804 + 332021805.

It is an arithmetic number, because the mean of its divisors is an integer number (332021805).

Almost surely, 2^664043609 is an apocalyptic number.

It is an amenable number.

664043609 is a deficient number, since it is larger than the sum of its proper divisors (1).

664043609 is an equidigital number, since it uses as much as digits as its factorization.

664043609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 93312, while the sum is 38.

The square root of 664043609 is about 25769.0436182641. The cubic root of 664043609 is about 872.4332328227.

The spelling of 664043609 in words is "six hundred sixty-four million, forty-three thousand, six hundred nine".