66766691 has 2 divisors, whose sum is σ = 66766692. Its totient is φ = 66766690.

The previous prime is 66766681. The next prime is 66766709. The reversal of 66766691 is 19666766.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66766691 - 2¹⁰ = 66765667 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66766621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33383345 + 33383346.

It is an arithmetic number, because the mean of its divisors is an integer number (33383346).

Almost surely, 2^66766691 is an apocalyptic number.

66766691 is a deficient number, since it is larger than the sum of its proper divisors (1).

66766691 is an equidigital number, since it uses as much as digits as its factorization.

66766691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 489888, while the sum is 47.

The square root of 66766691 is about 8171.0887279481. The cubic root of 66766691 is about 405.6828211032.

The spelling of 66766691 in words is "sixty-six million, seven hundred sixty-six thousand, six hundred ninety-one".