A millennial.
500th anniversary or celebration
It is a 500th year anniversary.
A quincentennial is 500 years. It signifies a significant milestone, usually associated with commemorating an event or anniversary that occurred 500 years ago.
The 2009 British Five Pound coin commemorated the 500th Anniversary of the accession of Henry VIII to the throne.
The Swiss Guard celebrated their 500th anniversary of protecting the Pope in 2006.
You haven't given enough information to fully identify the coin, but the words "quinto centenario" mean "quincentenary" (or "500th anniversary") in Spanish, so it is presumably a coin issued by a Spanish-speaking country in commemoration of the 500th anniversary of some historical event.
The word quincentennial means a period of 500 years. It can also be used to refer to a 500th anniversary.
The Christopher Columbus Voyage 500th Anniversary Glass Mug is a commemorative item that was likely produced and sold to mark the 500th anniversary of Christopher Columbus's first voyage to the Americas in 1492. The mug itself could have been manufactured anywhere in the world, and its specific origin would depend on the company or organization that created and distributed it.
It is called silver or silver year.
Don Cleveland Norman has written: 'The 500th anniversary pictorial census of the Gutenberg Bible' -- subject(s): Bible, Bibliography
3571 is the 500th prime number
Why is the 16th anniversary called tungsten