Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_18047346_4 (iata_code VARCHAR, passengers VARCHAR)
### Question:
If the passengers are 15,505,566, what is the iata code?
### Answer:
SELECT iata_code FROM table_18047346_4 WHERE passengers = "15,505,566"