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_13836704_7 (transit_passengers VARCHAR, airport VARCHAR)

### Question ###
How many different total number of transit passengers are there in London Luton?

### Accurate SQL ###

SELECT COUNT(transit_passengers) FROM table_13836704_7 WHERE airport = "London Luton"