CREATE TABLE table_16647 ("#" FLOAT, "Episode" TEXT, "Air Date" TEXT, "Rating" TEXT, "Share" FLOAT, "Rating/Share 18\\u201349" TEXT, "Viewers  ( m ) " TEXT, "Timeslot Rank" FLOAT, "Night Rank" TEXT, "Overall Rank" FLOAT)

what's the night rank with viewers (m) of 6.63
SELECT "Night Rank" FROM table_16647 WHERE "Viewers (m)" = '6.63'
SELECT "Night Rank" FROM "table_16647" WHERE "Viewers (m)" = '6.63'