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_13426649_1 ( original_air_date VARCHAR, _number VARCHAR )

### Question ###
How many different original air dates did the episode number 6 have?

### Accurate SQL ###

SELECT COUNT(original_air_date) FROM table_13426649_1 WHERE _number = 6