It's about thirty times the number of Elements on the Periodic Table.
In other words, 3,900 is 33.1 times the count of Elements on the Periodic Table, and the count of Elements on the Periodic Table is 0.0302 times that amount.(a.k.a. Periodic Table of the Elements, a.k.a chemical elements) (confirmed elements as of 2016)
From element number one, hydrogen, to element one-hundred eighteen, ununoctium, there are 118 confirmed elements on the Periodic Table. Ninety-four of the elements exist in nature, and the remaining twenty-four have only been synthesized in labs (not having occurred naturally in the time since scientists have begun researching them)
It's about forty times the number of Wolves in Yellowstone National Park.
In other words, 3,900 is 37.5 times the count of Wolves in Yellowstone National Park, and the count of Wolves in Yellowstone National Park is 0.0267 times that amount.(a.k.a. Henihco'oo; a.k.a. Héetíhco'oo) (December 2014 figures; Wyoming Park area)
As of the 2014 population count, there were 104 wolves living in Yellowstone National Park, in twelve packs. All of the wolves now living in the Park are thought to have descended from the 66 wolves (re)introduced into the Park in 1995-96.
It's about 45 times the number of Keys on a Piano.
It's about 55 times the number of Submarines in the US Navy.
It's about 70 times the number of Countries in Africa.
In other words, 3,900 is 72 times the count of Countries in Africa, and the count of Countries in Africa is 0.014 times that amount.(2016 figures) (sovereign states recognized by the UN only)
The continent of Africa includes 54 sovereign countries recognized by the United Nations as of 2016. It is the second-most populous continent in the world, with 1.1 billion inhabitants.
It's about 80 times the number of Teeth in a Great White Shark's Mouth.
In other words, 3,900 is 81 times the count of Teeth in a Great White Shark's Mouth, and the count of Teeth in a Great White Shark's Mouth is 0.012 times that amount.(Carcharodon carcharias) (average; including developing rows)
A Great White Shark has 48 exposed teeth on their upper and lower jaws. Behind these exposed teeth are developing teeth — up to 300 in about 5 rows. The sharks will continuously lose and replace the exposed teeth throughout their lives.
It's about 150 times the number of Countries in the European Union.
In other words, the count of Countries in the European Union is 0.0071 times 3,900.(a.k.a. EU) (2016 figures)
There are 28 member countries in the European Union, the latest member of which is Croatia. The EU is largely urban, with sixteen cities having a population of one million or more, and 75% of the population living in an urban area.