666604709 has 4 divisors (see below), whose sum is σ = 666661440. Its totient is φ = 666547980.

The previous prime is 666604669. The next prime is 666604727. The reversal of 666604709 is 907406666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 666604709 - 2⁸ = 666604453 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 666604709.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666604769) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3437 + ... + 36674.

It is an arithmetic number, because the mean of its divisors is an integer number (166665360).

Almost surely, 2^666604709 is an apocalyptic number.

It is an amenable number.

666604709 is a deficient number, since it is larger than the sum of its proper divisors (56731).

666604709 is a wasteful number, since it uses less digits than its factorization.

666604709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56730.

The product of its (nonzero) digits is 326592, while the sum is 44.

The square root of 666604709 is about 25818.6891417825. The cubic root of 666604709 is about 873.5534013943.

The spelling of 666604709 in words is "six hundred sixty-six million, six hundred four thousand, seven hundred nine".