Killynumber is a townland lying within the civil parish of Kilcronaghan, County Londonderry, Northern Ireland. It lies in the south-east with the civil parish of Desertmartin, and it is bounded by the townlands of Annagh & Moneysterlin, Coolsaragh, Drumsamney, Gortamney, and Killytoney. It was apportioned to the Drapers company as well as freeholds.