The Number 18Prime Factors of 18=2x3x3.
18 is a Pentagonal Pyramidal Number.
18 is a Heptagonal Number.
18 is an Abundant Number.
18 is a Lucas Number.
A Truncated Tetrahedron is an Archimedean Solid with 18 Edges.
18 is the only number that is twice the sum of its digits.
The Chemical Element Argon has an atomic number of 18.
The alphabet of the trees used by the druids for divinatory uses had eighteen letters, each letter deriving its name from the tree of which it is the initial. Composed of 5 vowels and 13 consonants, it formed a seasonal magic calendar of trees.
18 Melpomene is a large, bright Main belt asteroid named after Melpomene, the Muse of tragedy in Greek mythology.
The Year 18 ADIn the year 18 AD Caiaphas became the high priest of Jerusalem.
In the year 18 AD Strabo wrote Geographia