66681020291 has 2 divisors, whose sum is σ = 66681020292. Its totient is φ = 66681020290.

The previous prime is 66681020279. The next prime is 66681020297. The reversal of 66681020291 is 19202018666.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66681020291 is a prime.

It is a zygodrome in base 2.

It is not a weakly prime, because it can be changed into another prime (66681020297) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33340510145 + 33340510146.

It is an arithmetic number, because the mean of its divisors is an integer number (33340510146).

Almost surely, 2^66681020291 is an apocalyptic number.

66681020291 is a deficient number, since it is larger than the sum of its proper divisors (1).

66681020291 is an equidigital number, since it uses as much as digits as its factorization.

66681020291 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 62208, while the sum is 41.

The spelling of 66681020291 in words is "sixty-six billion, six hundred eighty-one million, twenty thousand, two hundred ninety-one".