question: How much Population (2011) has a Land area (km²) larger than 15.69, and a Population density (per km²) larger than 57.3?
answer: SELECT SUM(population__2011_) FROM table_name_28 WHERE land_area__km²_ > 15.69 AND population_density__per_km²_ > 57.3
context: CREATE TABLE table_name_28 (population__2011_ INTEGER, land_area__km²_ VARCHAR, population_density__per_km²_ VARCHAR)