66135566209 has 2 divisors, whose sum is σ = 66135566210. Its totient is φ = 66135566208.

The previous prime is 66135566113. The next prime is 66135566257. The reversal of 66135566209 is 90266553166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 65483274609 + 652291600 = 255897^2 + 25540^2 .

It is a cyclic number.

It is not a de Polignac number, because 66135566209 - 2¹⁷ = 66135435137 is a prime.

It is not a weakly prime, because it can be changed into another prime (66135566309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33067783104 + 33067783105.

It is an arithmetic number, because the mean of its divisors is an integer number (33067783105).

Almost surely, 2^66135566209 is an apocalyptic number.

It is an amenable number.

66135566209 is a deficient number, since it is larger than the sum of its proper divisors (1).

66135566209 is an equidigital number, since it uses as much as digits as its factorization.

66135566209 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 49.

The spelling of 66135566209 in words is "sixty-six billion, one hundred thirty-five million, five hundred sixty-six thousand, two hundred nine".