CREATE TABLE table_name_73 (population_in_millions VARCHAR, gdp_2012_millions_of_euro VARCHAR)

What is Population in Millions, when GDP 2012 Millions of Euro is 600,638?
SELECT population_in_millions FROM table_name_73 WHERE gdp_2012_millions_of_euro = "600,638"
SELECT "population_in_millions" FROM "table_name_73" WHERE "600,638" = "gdp_2012_millions_of_euro"