66681091 has 2 divisors, whose sum is σ = 66681092. Its totient is φ = 66681090.

The previous prime is 66681079. The next prime is 66681107. The reversal of 66681091 is 19018666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66681091 - 2⁵ = 66681059 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66681091.

It is not a weakly prime, because it can be changed into another prime (66681011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33340545 + 33340546.

It is an arithmetic number, because the mean of its divisors is an integer number (33340546).

Almost surely, 2^66681091 is an apocalyptic number.

66681091 is a deficient number, since it is larger than the sum of its proper divisors (1).

66681091 is an equidigital number, since it uses as much as digits as its factorization.

66681091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 66681091 is about 8165.8490679169. The cubic root of 66681091 is about 405.5093748324.

The spelling of 66681091 in words is "sixty-six million, six hundred eighty-one thousand, ninety-one".