166685009 has 2 divisors, whose sum is σ = 166685010. Its totient is φ = 166685008.

The previous prime is 166684961. The next prime is 166685039. The reversal of 166685009 is 900586661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 127057984 + 39627025 = 11272^2 + 6295^2 .

It is a cyclic number.

It is not a de Polignac number, because 166685009 - 2⁸ = 166684753 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (166685039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83342504 + 83342505.

It is an arithmetic number, because the mean of its divisors is an integer number (83342505).

Almost surely, 2^166685009 is an apocalyptic number.

It is an amenable number.

166685009 is a deficient number, since it is larger than the sum of its proper divisors (1).

166685009 is an equidigital number, since it uses as much as digits as its factorization.

166685009 is an evil number, because the sum of its binary digits is even.

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

The square root of 166685009 is about 12910.6548633290. The cubic root of 166685009 is about 550.3413957586.

The spelling of 166685009 in words is "one hundred sixty-six million, six hundred eighty-five thousand, nine".