66666666397 has 2 divisors, whose sum is σ = 66666666398. Its totient is φ = 66666666396.

The previous prime is 66666666379. The next prime is 66666666401. The reversal of 66666666397 is 79366666666.

Together with previous prime (66666666379) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59767536676 + 6899129721 = 244474^2 + 83061^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66666666397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66666666097) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33333333198 + 33333333199.

It is an arithmetic number, because the mean of its divisors is an integer number (33333333199).

Almost surely, 2^66666666397 is an apocalyptic number.

It is an amenable number.

66666666397 is a deficient number, since it is larger than the sum of its proper divisors (1).

66666666397 is an equidigital number, since it uses as much as digits as its factorization.

66666666397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 317447424, while the sum is 67.

The spelling of 66666666397 in words is "sixty-six billion, six hundred sixty-six million, six hundred sixty-six thousand, three hundred ninety-seven".