666228191 has 2 divisors, whose sum is σ = 666228192. Its totient is φ = 666228190.

The previous prime is 666228187. The next prime is 666228203. The reversal of 666228191 is 191822666.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 666228191 - 2² = 666228187 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666228151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333114095 + 333114096.

It is an arithmetic number, because the mean of its divisors is an integer number (333114096).

Almost surely, 2^666228191 is an apocalyptic number.

666228191 is a deficient number, since it is larger than the sum of its proper divisors (1).

666228191 is an equidigital number, since it uses as much as digits as its factorization.

666228191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 62208, while the sum is 41.

The square root of 666228191 is about 25811.3965333145. The cubic root of 666228191 is about 873.3889008438.

The spelling of 666228191 in words is "six hundred sixty-six million, two hundred twenty-eight thousand, one hundred ninety-one".