Thirty is a composite number, its proper divisors are 1, 2, 3, 5, 6, 10 and 15.

Also:

• 30 is a sphenic number: 30 = 2 × 3 × 5
• A dodecahedron, a icosahedron, a small stellated dodecahedron, a great dodecahedron, a great stellated dodecahedron, and a great icosahedron have 30 edges
• An icosidodecahedron, a dodecadodecahedron, a small icosahemidodecahedron, a small dodecahemidodecahedron, a great icosidodecahedron, a small dodecahemicosahedron, a great dodecahemicosahedron, a great icosahemidodecahedron, and a great dodecahemidodecahedron have 30 vertices
• A rhombicosidodecahedron, a truncated icosidodecahedron, a small rhombidodecahedron, a rhombidodecadodecahedron, a rhombicosahedron, a quasitruncated dodecahedron, a quasirhombicosidodecahedron, a great quasitruncated icosidodecahedron, and a great rhombidodecahedron have 30 squares.