Yes, it is possible. Go to window 1, and then type: :number 7. If there is already a window at 7, then the two windows will be swapped (window 7 will become window 1). From the manpage:
Change the current windows number. If the given number n is already
used by another window, both windows exchange their numbers. If no
argument is specified, the current window number (and title) is shown.