The ETA caliber 2836-2 can have 17, 21, or 25 jewels.
There is a less common COSC caliber as well as non-COSC.
These are photos of the caliber 2836-2 found in this Swiss Legend Abyssos dive watch, 25 jewels with an Incabloc Novodiac shock absorber.
Pictured below is a 25 jewels COSC example of the ETA caliber 2836-2 found in a BALL Cleveland Express. 28,800 VPH, Incabloc shock absorber.