30 is a square pyramidal number. 30 30th birthday cake an even, composite, pronic number.

It has an aliquot sum of 42, which is the second sphenic number. The largest number such that all coprimes smaller than itself, except for 1, are prime. The sum of the first four squares, making it a square pyramidal number. The measure of the central angle and exterior angle of a dodecagon, which is the petrie polygon of the 24-cell. The number of sides of a triacontagon, which in turn is the petrie polygon of the 120-cell and 600-cell. The number of sides of a dodecahedron and icosahedron, of vertices of an icosidodecahedron, and of faces of a rhombic dodecahedron.

The sum of the number of elements of a 5-cell: 5 vertices, 10 edges, 10 faces, and 5 cells. 30 is the only number less than 60 that is neither a prime nor of the aforementioned form. Therefore, 30 is the only candidate for the order of a simple group less than 60, in which one needs other methods to specifically reject to eventually deduce said order. Look up thirty in Wiktionary, the free dictionary. The atomic number of zinc is 30. Messier object M30, a magnitude 8. The minimum age for United States senators.