icosihenagon= 21-sided polygon icosihenagon= 21-sided polygon
I would just call it an "800-sided polygon."
The name of a sided polygon is Octaconpentagon.
It's perfectly acceptable to call it a 70-agon but what is more important is that you can work out its properties
The name of a 18 sided polygon is Octadecagon.
The name of a 45 sided polygon is Tetraconpentagon.
The name of a 7 sided polygon is Heptagon.
The name of a 10 sided polygon is Decagon.
The name of a 8 sided polygon is Octagon.
The name of a 33 sided polygon is riacontakaitrigon.
A 10-sided polygon is called a decagon.
The name of a 262 sided polygon is dihectrahexacontadigon.