866009 has 2 divisors, whose sum is σ = 866010. Its totient is φ = 866008.

The previous prime is 866003. The next prime is 866011. The reversal of 866009 is 900668.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 760384 + 105625 = 872^2 + 325^2 .

It is a cyclic number.

It is not a de Polignac number, because 866009 - 2⁴ = 865993 is a prime.

Together with 866011, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (866003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433004 + 433005.

It is an arithmetic number, because the mean of its divisors is an integer number (433005).

2⁸⁶⁶⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

866009 is a deficient number, since it is larger than the sum of its proper divisors (1).

866009 is an equidigital number, since it uses as much as digits as its factorization.

866009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 866009 is about 930.5960455536. The cubic root of 866009 is about 95.3178274725.

The spelling of 866009 in words is "eight hundred sixty-six thousand, nine".