66690191 has 2 divisors, whose sum is σ = 66690192. Its totient is φ = 66690190.

The previous prime is 66690187. The next prime is 66690203. The reversal of 66690191 is 19109666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66690191 - 2² = 66690187 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66690101) 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, 33345095 + 33345096.

It is an arithmetic number, because the mean of its divisors is an integer number (33345096).

Almost surely, 2^66690191 is an apocalyptic number.

66690191 is a deficient number, since it is larger than the sum of its proper divisors (1).

66690191 is an equidigital number, since it uses as much as digits as its factorization.

66690191 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496, while the sum is 38.

The square root of 66690191 is about 8166.4062475486. The cubic root of 66690191 is about 405.5278206786.

The spelling of 66690191 in words is "sixty-six million, six hundred ninety thousand, one hundred ninety-one".