I can create 60 folders across 7 pages of 15 tiles. Each folder visually has 4 pages of 15 tiles, so 60 folders x 60 tiles, plus 7 pages of 15 tiles on the main menu, minus the tiles taken by the 60 folders, is 3645.
Of course it doesn't matter how many tile spaces you can see if the system only lets you fill a certain number of them.