66566909 has 2 divisors, whose sum is σ = 66566910. Its totient is φ = 66566908.

The previous prime is 66566879. The next prime is 66566911. The reversal of 66566909 is 90966566.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64850809 + 1716100 = 8053^2 + 1310^2 .

It is a cyclic number.

It is not a de Polignac number, because 66566909 - 2⁸ = 66566653 is a prime.

Together with 66566911, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66566939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33283454 + 33283455.

It is an arithmetic number, because the mean of its divisors is an integer number (33283455).

Almost surely, 2^66566909 is an apocalyptic number.

It is an amenable number.

66566909 is a deficient number, since it is larger than the sum of its proper divisors (1).

66566909 is an equidigital number, since it uses as much as digits as its factorization.

66566909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 524880, while the sum is 47.

The square root of 66566909 is about 8158.8546377540. The cubic root of 66566909 is about 405.2777833152.

The spelling of 66566909 in words is "sixty-six million, five hundred sixty-six thousand, nine hundred nine".