664787609 has 2 divisors, whose sum is σ = 664787610. Its totient is φ = 664787608.

The previous prime is 664787593. The next prime is 664787689. The reversal of 664787609 is 906787466.

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., 659051584 + 5736025 = 25672^2 + 2395^2 .

It is a cyclic number.

It is not a de Polignac number, because 664787609 - 2⁴ = 664787593 is a prime.

It is not a weakly prime, because it can be changed into another prime (664787689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332393804 + 332393805.

It is an arithmetic number, because the mean of its divisors is an integer number (332393805).

Almost surely, 2^664787609 is an apocalyptic number.

It is an amenable number.

664787609 is a deficient number, since it is larger than the sum of its proper divisors (1).

664787609 is an equidigital number, since it uses as much as digits as its factorization.

664787609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3048192, while the sum is 53.

The square root of 664787609 is about 25783.4755027324. The cubic root of 664787609 is about 872.7589383696.

The spelling of 664787609 in words is "six hundred sixty-four million, seven hundred eighty-seven thousand, six hundred nine".