866040209 has 2 divisors, whose sum is σ = 866040210. Its totient is φ = 866040208.

The previous prime is 866040139. The next prime is 866040247. The reversal of 866040209 is 902040668.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 763969600 + 102070609 = 27640^2 + 10103^2 .

It is a cyclic number.

It is not a de Polignac number, because 866040209 - 2¹² = 866036113 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (866040289) 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, 433020104 + 433020105.

It is an arithmetic number, because the mean of its divisors is an integer number (433020105).

Almost surely, 2^866040209 is an apocalyptic number.

It is an amenable number.

866040209 is a deficient number, since it is larger than the sum of its proper divisors (1).

866040209 is an equidigital number, since it uses as much as digits as its factorization.

866040209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 866040209 is about 29428.5611099150. The cubic root of 866040209 is about 953.1897247154.

The spelling of 866040209 in words is "eight hundred sixty-six million, forty thousand, two hundred nine".