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_name_21 (tie_no VARCHAR, home_team VARCHAR)
### Question:
What is the tie number when Wigan Athletic is the home team?
### Answer:
SELECT tie_no FROM table_name_21 WHERE home_team = "wigan athletic"