Which Object type has an NGC number of 2171?
CREATE TABLE "2101_2200" (
  "ngc_number" real,
  "object_type" text,
  "constellation" text,
  "right_ascension_j2000" text,
  "declination_j2000" text
);
SELECT "object_type" FROM "2101_2200" WHERE "ngc_number"=2171;