666630191 has 2 divisors, whose sum is σ = 666630192. Its totient is φ = 666630190.

The previous prime is 666630149. The next prime is 666630227. The reversal of 666630191 is 191036666.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 666630191 - 2⁶ = 666630127 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666630491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333315095 + 333315096.

It is an arithmetic number, because the mean of its divisors is an integer number (333315096).

Almost surely, 2^666630191 is an apocalyptic number.

666630191 is a deficient number, since it is larger than the sum of its proper divisors (1).

666630191 is an equidigital number, since it uses as much as digits as its factorization.

666630191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34992, while the sum is 38.

The square root of 666630191 is about 25819.1826168064. The cubic root of 666630191 is about 873.5645322308.

The spelling of 666630191 in words is "six hundred sixty-six million, six hundred thirty thousand, one hundred ninety-one".