<|im_start|>user
How many cities in the world have a population exceeding 5 million people ?

Context:
There are 81 cities in the world with a population exceeding 5 million people.<|im_end|>
<|im_start|>assistant
There are 81 cities in the world with a population exceeding 5 million people, according to 2018 estimates by the United Nations. The U.N. figures include a mixture of city proper, metropolitan area, and urban area.<|im_end|>
