Need to add space after every 4th Character

Hi all

I'm hoping this is an easy one for you.

I have some numbers like

IR8930004009260000099186613

But i need to add spaces after EVERY 4th Character, like this:

IR89 3000 4009 2600 0009 9186 613

The length of the value will vary, so it could be say 22 characters, or it maybe 24 etc

How can this be achieved?

Thanks in advance