664005409 has 2 divisors, whose sum is σ = 664005410. Its totient is φ = 664005408.

The previous prime is 664005389. The next prime is 664005421. The reversal of 664005409 is 904500466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 644398225 + 19607184 = 25385^2 + 4428^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664005409 is a prime.

It is not a weakly prime, because it can be changed into another prime (664005479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332002704 + 332002705.

It is an arithmetic number, because the mean of its divisors is an integer number (332002705).

Almost surely, 2^664005409 is an apocalyptic number.

It is an amenable number.

664005409 is a deficient number, since it is larger than the sum of its proper divisors (1).

664005409 is an equidigital number, since it uses as much as digits as its factorization.

664005409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 664005409 is about 25768.3024081913. The cubic root of 664005409 is about 872.4165032042.

The spelling of 664005409 in words is "six hundred sixty-four million, five thousand, four hundred nine".