Imaginary Number Do some research on other important constants in mathematics. A good constant has a specific name and is important in mathematical formula

Imaginary Number Do some research on other important constants in mathematics. A good constant has a specific name and is important in mathematical formulas. Do not choose pi or e.
Share with us what you have found out about the number; for example, its history, some trivial facts about the number, and/or how it is applied. Be sure to include your sources so others can do further research.
To get you started in your research, below are some sources you can use:

http://www.popularmechanics.com/flight/g163/13-most-important-numbers-in-the-universe/
https://en.wikipedia.org/wiki/Mathematical_constant#Table_of_selected_mathematical_constants