How many million viewers watched episode number 20?
CREATE TABLE table_2405 (
    "Episode No." real,
    "Series No." real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Viewers (millions)" text,
    "Original airdate" text
)
SELECT "Viewers (millions)" FROM table_2405 WHERE "Episode No." = '20'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: How many million viewers watched episode number 20? ### Input: CREATE TABLE table_2405 (
    "Episode No." real,
    "Series No." real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Viewers (millions)" text,
    "Original airdate" text
) ### Response: SELECT "Viewers (millions)" FROM table_2405 WHERE "Episode No." = '20'