Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_25391981_20 ( episode_number VARCHAR, episode VARCHAR )

### Question ###
What number episode was Week 4, Part 2?

### Accurate SQL ###

SELECT episode_number FROM table_25391981_20 WHERE episode = "Week 4, Part 2"