CREATE TABLE table_29541 ("No. in series" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Prod. No." FLOAT, "Viewers  ( millions ) " TEXT)

How many episodes have 18.73 million viewers?
SELECT COUNT("No. in series") FROM table_29541 WHERE "Viewers (millions)" = '18.73'
SELECT COUNT("No. in series") FROM "table_29541" WHERE "Viewers (millions)" = '18.73'