**8666**= 2 x 7 x 619.

**8666**has a 9th root whose decimal part starts with the digits 1 to 9 in some order.

**8666**is a beastly number (A051003).

**8666**is the number of permutations of length 21 that avoid the patterns 123 and 4312 (A116699).

**8666**is a number

*n*such that

*n*,

*n*+ 1,

*n*+ 2, and

*n*+ 3 are not divisible by any of their nonzero digits (A244358).

**8666**is a number

*n*such that

*n*ends with 6 and is the difference of cubes in at least one way (A038861).

Source: What's Special About This Number?