866689 has 2 divisors, whose sum is σ = 866690. Its totient is φ = 866688.

The previous prime is 866683. The next prime is 866693. The reversal of 866689 is 986668.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 497025 + 369664 = 705^2 + 608^2 .

It is a cyclic number.

It is not a de Polignac number, because 866689 - 2¹¹ = 864641 is a prime.

It is a super-2 number, since 2×866689² = 1502299645442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (866683) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433344 + 433345.

It is an arithmetic number, because the mean of its divisors is an integer number (433345).

2⁸⁶⁶⁶⁸⁹ is an apocalyptic number.

It is an amenable number.

866689 is a deficient number, since it is larger than the sum of its proper divisors (1).

866689 is an equidigital number, since it uses as much as digits as its factorization.

866689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 124416, while the sum is 43.

The square root of 866689 is about 930.9613310981. The cubic root of 866689 is about 95.3427691553.

The spelling of 866689 in words is "eight hundred sixty-six thousand, six hundred eighty-nine".