6 = sides on a hexagon
7 = sides on a heptagon
but guess you have covered all these and don't suppose 64 could be the number of squares on a chess board
The old-fashioned eau de cologne 4711 was named after the number of the house the inventor lived in. Are there any other 'etc' categories to cover an address? It seems to be quite an unusual number to have another meaning, somehow!!?