Retrieve the ten largest cities in the world.
According to the United Nations data in 2020, the ten largest cities in the world and their estimated population numbers are:

1. Tokyo, Japan (37,400,068)
2. Delhi, India (30,290,936)
3. Shanghai, China (27,058,479)
4. São Paulo, Brazil (22,043,028)
5. Mumbai, India (20,411,274)
6. Beijing, China (20,384,336)
7. Cairo, Egypt (20,075,000)
8. Osaka, Japan (19,281,343)
9. New York, United States (18,804,000)
10. Karachi, Pakistan (16,094,000)
Complete the following task based on the instruction and optional input provided.### Instruction:
Retrieve the ten largest cities in the world.

### Output:
According to the United Nations data in 2020, the ten largest cities in the world and their estimated population numbers are:

1. Tokyo, Japan (37,400,068)
2. Delhi, India (30,290,936)
3. Shanghai, China (27,058,479)
4. São Paulo, Brazil (22,043,028)
5. Mumbai, India (20,411,274)
6. Beijing, China (20,384,336)
7. Cairo, Egypt (20,075,000)
8. Osaka, Japan (19,281,343)
9. New York, United States (18,804,000)
10. Karachi, Pakistan (16,094,000)