CREATE TABLE table_65739 ("Place" TEXT, "Code" FLOAT, "Area  ( km 2  ) " FLOAT, "Population" FLOAT, "Most spoken language" TEXT)

What's the most area of Bochum Part 2 with a population less than 15,911?
SELECT MAX("Area (km 2 )") FROM table_65739 WHERE "Place" = 'bochum part 2' AND "Population" < '15,911'
SELECT MAX("Area (km 2 )") FROM "table_65739" WHERE "Place" = 'bochum part 2' AND "Population" < '15,911'