It's about twenty times the number of Keys on a Piano.
In other words, the count of Keys on a Piano is 0.042 times 2,100.(Moden layout; A0 to C7)
It's about one-twenty-fifth the number of Seats in The Colosseum.
In other words, the count of Seats in The Colosseum is 30 times 2,100.(a.k.a. The Coliseum, a.k.a. Flavian Amphitheatre, a.k.a. Amphitheatrum Flavium, a.k.a. Anfiteatro Flavio or Colosseo) (Rome) (estimated)
It's about thirty times the number of Submarines in the US Navy.
In other words, the count of Submarines in the US Navy is 0.034 times 2,100.(a.k.a. Subs) (includes all types, all classes) (2015 figures)
It's about one-fortieth the number of Seats in Lambeau Field.
In other words, 2,100 is 0.026011 times the count of Seats in Lambeau Field, and the count of Seats in Lambeau Field is 38.4450 times that amount.(2014 figures) (a.k.a. City Stadium, a.k.a. New City Stadium, a.k.a. Titletown USA, a.k.a. The Frozen Tundra, a.k.a. The Shrine of Pro Football) (Green Bay, Wisconsin)
Lambeau Field, home of the Green Bay Packers NFL team, can accommodate 80,735 spectators. With 58 years of occupancy by the Packers, Lambeau Field holds the record as the longest consecutive home of any NFL team.
It's about forty times the number of Countries in Africa.
In other words, the count of Countries in Africa is 0.026 times 2,100.(2016 figures) (sovereign states recognized by the UN only)
It's about 45 times the number of Teeth in a Great White Shark's Mouth.
In other words, the count of Teeth in a Great White Shark's Mouth is 0.023 times 2,100.(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 75 times the number of Countries in the European Union.
In other words, the count of Countries in the European Union is 0.013 times 2,100.(a.k.a. EU) (2016 figures)