166865009 has 2 divisors, whose sum is σ = 166865010. Its totient is φ = 166865008.

The previous prime is 166865003. The next prime is 166865063. The reversal of 166865009 is 900568661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 90250000 + 76615009 = 9500^2 + 8753^2 .

It is a cyclic number.

It is not a de Polignac number, because 166865009 - 2¹² = 166860913 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (166865003) 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, 83432504 + 83432505.

It is an arithmetic number, because the mean of its divisors is an integer number (83432505).

Almost surely, 2^166865009 is an apocalyptic number.

It is an amenable number.

166865009 is a deficient number, since it is larger than the sum of its proper divisors (1).

166865009 is an equidigital number, since it uses as much as digits as its factorization.

166865009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 77760, while the sum is 41.

The square root of 166865009 is about 12917.6239688265. The cubic root of 166865009 is about 550.5394255935.

The spelling of 166865009 in words is "one hundred sixty-six million, eight hundred sixty-five thousand, nine".