66665605109 has 2 divisors, whose sum is σ = 66665605110. Its totient is φ = 66665605108.

The previous prime is 66665605103. The next prime is 66665605117. The reversal of 66665605109 is 90150656666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43888155025 + 22777450084 = 209495^2 + 150922^2 .

It is a cyclic number.

It is not a de Polignac number, because 66665605109 - 2¹⁶ = 66665539573 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66665605103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33332802554 + 33332802555.

It is an arithmetic number, because the mean of its divisors is an integer number (33332802555).

Almost surely, 2^66665605109 is an apocalyptic number.

It is an amenable number.

66665605109 is a deficient number, since it is larger than the sum of its proper divisors (1).

66665605109 is an equidigital number, since it uses as much as digits as its factorization.

66665605109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1749600, while the sum is 50.

The spelling of 66665605109 in words is "sixty-six billion, six hundred sixty-five million, six hundred five thousand, one hundred nine".