66108209 has 2 divisors, whose sum is σ = 66108210. Its totient is φ = 66108208.

The previous prime is 66108191. The next prime is 66108247. The reversal of 66108209 is 90280166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 59243809 + 6864400 = 7697^2 + 2620^2 .

It is a cyclic number.

It is not a de Polignac number, because 66108209 - 2⁸ = 66107953 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (66108109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33054104 + 33054105.

It is an arithmetic number, because the mean of its divisors is an integer number (33054105).

Almost surely, 2^66108209 is an apocalyptic number.

It is an amenable number.

66108209 is a deficient number, since it is larger than the sum of its proper divisors (1).

66108209 is an equidigital number, since it uses as much as digits as its factorization.

66108209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 66108209 is about 8130.6954807077. The cubic root of 66108209 is about 404.3447393202.

The spelling of 66108209 in words is "sixty-six million, one hundred eight thousand, two hundred nine".