66991307 has 2 divisors, whose sum is σ = 66991308. Its totient is φ = 66991306.

The previous prime is 66991273. The next prime is 66991313. The reversal of 66991307 is 70319966.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66991307 - 2⁸ = 66991051 is a prime.

It is not a weakly prime, because it can be changed into another prime (66991367) 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, 33495653 + 33495654.

It is an arithmetic number, because the mean of its divisors is an integer number (33495654).

Almost surely, 2^66991307 is an apocalyptic number.

66991307 is a deficient number, since it is larger than the sum of its proper divisors (1).

66991307 is an equidigital number, since it uses as much as digits as its factorization.

66991307 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 61236, while the sum is 41.

The square root of 66991307 is about 8184.8217451573. The cubic root of 66991307 is about 406.1372435945.

The spelling of 66991307 in words is "sixty-six million, nine hundred ninety-one thousand, three hundred seven".