Yes! You can definitely change and customize integers.
Its a little tricky to explain how you have to do this in the Numbers interface but follow below:
Select cells or table > open Inspector > select Cells tab (4th from the left) > Use the drop down list under "Cell Format" and select "Custom" at the bottom....
From here you can edit your own intergers by dragging elements from below onto the field above (See example below). Don't worry if the elements do NOT match what you want below... You add the element by dragging it, THEN once in the field you can click on it and edit how many digits there are, as represented by '#' simply by pressing Up and Down on the keyboard, Or clicking on its own little drop down arrow to access features like "Remove separator". Then in between these elements simply type a comma " , " and drag the next element, keep editing away like that and you should get something like what I have below:
Feel free to ask any more questions PrashKot :]