Although not as famous as pi or e, the Euler-Mascheroni constant is just as fascinating and plays and important role in many areas of mathematics.
My other YouTube channels:
The Science Fiction Rock Experience ( the music show I produce):
https://www.youtube.com/@ScienceFictionRockExperience
My science and music channel::
https://www.youtube.com/@drdaviddarling
Science World (with Emrah Polat):
https://www.youtube.com/@ScienceWorld1
My website: https://www.daviddarling.info
My latest book is available here: https://oneworld-publications.com/work/the-biggest-number-in-the-world/