66565691 has 2 divisors, whose sum is σ = 66565692. Its totient is φ = 66565690.

The previous prime is 66565679. The next prime is 66565753. The reversal of 66565691 is 19656566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66565691 - 2¹⁸ = 66303547 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66565621) 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, 33282845 + 33282846.

It is an arithmetic number, because the mean of its divisors is an integer number (33282846).

Almost surely, 2^66565691 is an apocalyptic number.

66565691 is a deficient number, since it is larger than the sum of its proper divisors (1).

66565691 is an equidigital number, since it uses as much as digits as its factorization.

66565691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 291600, while the sum is 44.

The square root of 66565691 is about 8158.7799945825. The cubic root of 66565691 is about 405.2753114596.

The spelling of 66565691 in words is "sixty-six million, five hundred sixty-five thousand, six hundred ninety-one".