Monaco is the oldest country in the world by median age.
It is also the only country where the median age is over 50.
Niger is the youngest country in the world - the median age, according to the CIA World Factbook, is 15.3.
We learned this because of a particularly interesting post in one of our favourite subreddits.
The post is derived from the CIA World Factbook and highlights the difference in the average ages of countries.
It's notable how old Europe is in comparison to countries in Africa and in South East Asia - one of the challenges facing the continent in coming years will be an ageing population.
View the map, below: