Perl follows the exact same model for numbers.

No, it doesn't. As I demonstrated above, variables holdiing numeric values are **NOT** immutable. Constants are (to use your own word) obviously immutable. But variables are not constants. And variables are not immutable.

Also declaring something that contradicts your line of thought as "meaningless" without any explanation isn't very good style of discussion.

No explanation is necessary. You already demonstrated above that you know this is nothing more than an obvious non sequitur to the threads subject. Hence, further discussion is meaningless and pointless.