666506189 has 2 divisors, whose sum is σ = 666506190. Its totient is φ = 666506188.

The previous prime is 666506041. The next prime is 666506219. The reversal of 666506189 is 981605666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 394816900 + 271689289 = 19870^2 + 16483^2 .

It is a cyclic number.

It is not a de Polignac number, because 666506189 - 2⁸ = 666505933 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666506989) 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, 333253094 + 333253095.

It is an arithmetic number, because the mean of its divisors is an integer number (333253095).

Almost surely, 2^666506189 is an apocalyptic number.

It is an amenable number.

666506189 is a deficient number, since it is larger than the sum of its proper divisors (1).

666506189 is an equidigital number, since it uses as much as digits as its factorization.

666506189 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 466560, while the sum is 47.

The square root of 666506189 is about 25816.7811510266. The cubic root of 666506189 is about 873.5103640339.

The spelling of 666506189 in words is "six hundred sixty-six million, five hundred six thousand, one hundred eighty-nine".