Is a 2.5 liter 6 cylinder?

No, a 2.5 liter engine is not necessarily a 6 cylinder. The number of cylinders in an engine is not directly related to its displacement (engine size). There are 4 cylinder 2.5 liter engines, as well as 6 cylinder 2.5 liter engines, and even other configurations such as 5 cylinder or 8 cylinder engines that could have a 2.5 liter displacement. The number of cylinders and the engine displacement are two separate specifications of an engine design.