From the viewpoint of genetics the usual guess is that you want 50 to 500 indivi...

From the viewpoint of genetics the usual guess is that you want 50 to 500 individuals to build a population.

https://www.britannica.com/science/minimum-viable-population...

If people were attempting interplanetary/interstellar colonization or planning for a serious interruption they could possibly stockpile millions of human eggs.