CREATE TABLE table_73918 ("Outcome" TEXT, "No." TEXT, "Date" TEXT, "Championship" TEXT, "Surface" TEXT, "Opponent in the final" TEXT, "Score in the final" TEXT)

On the date October 21, 2007, what is the No.?
SELECT "No." FROM table_73918 WHERE "Date" = 'October 21, 2007'
SELECT "No." FROM "table_73918" WHERE "Date" = 'October 21, 2007'