665263609 has 2 divisors, whose sum is σ = 665263610. Its totient is φ = 665263608.

The previous prime is 665263603. The next prime is 665263633. The reversal of 665263609 is 906362566.

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., 655360000 + 9903609 = 25600^2 + 3147^2 .

It is a cyclic number.

It is not a de Polignac number, because 665263609 - 2⁷ = 665263481 is a prime.

It is not a weakly prime, because it can be changed into another prime (665263603) 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, 332631804 + 332631805.

It is an arithmetic number, because the mean of its divisors is an integer number (332631805).

Almost surely, 2^665263609 is an apocalyptic number.

It is an amenable number.

665263609 is a deficient number, since it is larger than the sum of its proper divisors (1).

665263609 is an equidigital number, since it uses as much as digits as its factorization.

665263609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 349920, while the sum is 43.

The square root of 665263609 is about 25792.7045693157. The cubic root of 665263609 is about 872.9671924224.

The spelling of 665263609 in words is "six hundred sixty-five million, two hundred sixty-three thousand, six hundred nine".