CREATE TABLE table_2405 ("Episode No." FLOAT, "Series No." FLOAT, "Title" CLOB, "Directed by" CLOB, "Written by" CLOB, "Viewers  ( millions ) " CLOB, "Original airdate" CLOB)

How many million viewers watched episode number 20?
SELECT "Viewers (millions)" FROM table_2405 WHERE "Episode No." = '20'
SELECT "Viewers (millions)" FROM "table_2405" WHERE "Episode No." = '20'