Those who complete (compleat!) the Munros can record this fact and receive the magic number by writing in to The Clerk of The List (See here). Additionally, a list of current compleaters is published annually in the SMC Journal.
H.H. Tsai - 717
Sgurr Mor (Loch Quoich) - 1989
Dr Tsai reckons that not many Munroists choose this remote summit for their final Munro - and he's probably right!