CREATE TABLE table_17658 ("Series #" FLOAT, "Season #" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Total viewers  ( in millions ) " TEXT)

How many millions of total viewers watched series #57?
SELECT COUNT("Total viewers (in millions)") FROM table_17658 WHERE "Series #" = '57'
SELECT COUNT("Total viewers (in millions)") FROM "table_17658" WHERE "Series #" = '57'