This is a question I discuss in my book Likutay Nanach (available for free download at nanach.org).
This Shabos I was graced by the startling revelation that the numerical value (gimatria) for Na Nach Nachma Nachman MeUman, when using the full value of the final Nun - 700, is 1791. In 1791 Rabbainu was aproximately 18 years old! And in the tenth year following, Rabbainu (apr. 27) visited Rabbi Shimon Bar Yochai in Meron, and Rabbi Shimon asked him, Meron, Me Ron? - who is singing, and Rabbi Nachman revealed to Rabbi Shimon that it was he!