Primary Class Constructors in Kotlin

I still have doubts about val and var. Parameter is var in constructor, but object is val. I was able to reassign the parameter using object reference. Then what does immutability here apply to?
My code:
class ClassConstr constructor(var parm1: Int, val parm2:Double, val parm3:String)

//inside main
val emptyWContr = ClassConst
emptyWContr.parm1 = 2
println(emptyWContr.parm1)

Great content!! Keep rockin Kotlin