What is a 20 sided shape called?

A 20-sided shape is called an icosagon. It is a polygon with 20 sides, 20 vertices, and 20 interior angles. Each interior angle of an icosagon measures 162 degrees. The sum of all the interior angles of an icosagon is 3240 degrees. An icosagon can be regular or irregular, depending on whether all sides and angles are equal in measure. Regular icosagons have all sides and angles equal, while irregular icosagons have varying side lengths and angles.