by vince choi
this flow will check a number if it is ODD or EVEN, PRIME or COMPOSITE.
in theory, the time of computation can be cut off greatly using FERMAT'S LITTLE THEOREM(future update perhaps) if we are dealing with extremely huge numbers, e.g. quadrillions, etc., but this flow is useful until 999 999 999 999 999. So, you dont have to worry about that.