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_56 (laps INTEGER, grid VARCHAR, time_retired VARCHAR)
### Question:
What is the mean number of laps when the grid is less than 19 and time/retired is +21.3 secs?
### Answer:
SELECT AVG(laps) FROM table_name_56 WHERE grid < 19 AND time_retired = "+21.3 secs"