A 20-sided polygon is called an icosagon. Along with having 20 sides, all icosagons have 20 interior angles that add up to a total of 3240 degrees.
Regular icosagons have sides of equal length and identical interior angles, each of which measures 162 degrees. Irregular icosagons on the other hand, have sides and angles of varying lengths. A famous example of an irregular icosagon is a swastika. Although this symbol has become stigmatized in the Western world because of its association with the Nazi Party, it has a long history of use in multiple cultures. For instance, in India swastikas are used to represent prosperity and well-being.