666880217 has 2 divisors, whose sum is σ = 666880218. Its totient is φ = 666880216.

The previous prime is 666880213. The next prime is 666880229. The reversal of 666880217 is 712088666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 448550041 + 218330176 = 21179^2 + 14776^2 .

It is a cyclic number.

It is not a de Polignac number, because 666880217 - 2² = 666880213 is a prime.

It is a super-4 number, since 4×666880217⁴ (a number of 36 digits) contains 4444 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (666880213) 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, 333440108 + 333440109.

It is an arithmetic number, because the mean of its divisors is an integer number (333440109).

Almost surely, 2^666880217 is an apocalyptic number.

It is an amenable number.

666880217 is a deficient number, since it is larger than the sum of its proper divisors (1).

666880217 is an equidigital number, since it uses as much as digits as its factorization.

666880217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 193536, while the sum is 44.

The square root of 666880217 is about 25824.0240280248. The cubic root of 666880217 is about 873.6737314782.

The spelling of 666880217 in words is "six hundred sixty-six million, eight hundred eighty thousand, two hundred seventeen".