666979009 has 2 divisors, whose sum is σ = 666979010. Its totient is φ = 666979008.

The previous prime is 666979007. The next prime is 666979013. The reversal of 666979009 is 900979666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 514382400 + 152596609 = 22680^2 + 12353^2 .

It is a cyclic number.

It is not a de Polignac number, because 666979009 - 2¹ = 666979007 is a prime.

Together with 666979007, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (666979007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333489504 + 333489505.

It is an arithmetic number, because the mean of its divisors is an integer number (333489505).

Almost surely, 2^666979009 is an apocalyptic number.

It is an amenable number.

666979009 is a deficient number, since it is larger than the sum of its proper divisors (1).

666979009 is an equidigital number, since it uses as much as digits as its factorization.

666979009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1102248, while the sum is 52.

The square root of 666979009 is about 25825.9367497096. The cubic root of 666979009 is about 873.7168715161.

The spelling of 666979009 in words is "six hundred sixty-six million, nine hundred seventy-nine thousand, nine".