A fan includes a hub rotatable about an axis and having an open end and a closed end, and a plurality of blades extending from the hub. Each of the blades has a leading side surface, a trailing side surface, an inner lateral edge corresponding to the open end of the hub, an outer lateral edge corresponding to the closed end of the hub, and a radial outer edge having opposite inner and outer ends connected respectively to the inner and outer lateral edges, and at least one end portion extending from one of the inner and outer ends toward both the axis and one of the inner and outer lateral edges.