869 = 11 x 79.
869 is the number of different resistances that can be created in a circuit of nine equal resistors (A048211).
The sum of the digits of 869 equals the sum of the digits of the 869th prime (6737) (A033549). 869 and the 869th prime (6737) have only the digit 6 in common (A107937).
869 is a number that yields a prime when 0 is inserted anywhere in it (but not added to the end or beginning) (A216169).
Source: What's Special About This Number?