Cutting insert, cutting tool, and method of manufacturing machined product

A cutting insert, comprising:

• an upper surface, a lower surface and a side surface located between the upper surface and the lower surface, and a polygonal plate-shaped in which a cutting edge is formed at an intersection of the upper surface and the side surface,
• wherein the upper surface comprises a convex-shaped main part comprising a flat upper end surface, a first projection projecting from the main part to a corner part of the upper surface in a top plan view, a second projection projecting from the first projection toward the corner part in the top plan view, and a pair of third projections respectively projecting from the first projection toward a periphery of the upper surface so as to interpose at least a part of the second projection between the pair of third projections in the top plan view, and
• wherein a surface of the first projection is an inclined surface curved in a concave shape, and a surface of the second projection is a planar inclined surface in a portion located on a bisector of the corner part in the top plan view.