66681468209 has 2 divisors, whose sum is σ = 66681468210. Its totient is φ = 66681468208.

The previous prime is 66681468059. The next prime is 66681468277. The reversal of 66681468209 is 90286418666.

66681468209 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66269175184 + 412293025 = 257428^2 + 20305^2 .

It is a cyclic number.

It is not a de Polignac number, because 66681468209 - 2²⁸ = 66413032753 is a prime.

It is not a weakly prime, because it can be changed into another prime (66681468289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33340734104 + 33340734105.

It is an arithmetic number, because the mean of its divisors is an integer number (33340734105).

Almost surely, 2^66681468209 is an apocalyptic number.

It is an amenable number.

66681468209 is a deficient number, since it is larger than the sum of its proper divisors (1).

66681468209 is an equidigital number, since it uses as much as digits as its factorization.

66681468209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5971968, while the sum is 56.

The spelling of 66681468209 in words is "sixty-six billion, six hundred eighty-one million, four hundred sixty-eight thousand, two hundred nine".