Attributes of companies that spawn a lot of successful entrepreneurs

I want to go to a fast growth company that will spawn a lot of future entrepreneurs and where there’ll be a strong alumni network.

Wondering what qualities I should look for when interviewing and researching companies.

Some examples:
PayPal, Pre-2011 Google, FB, Square, Airbnb (coinbase, mesosphere founders came from there)

Suggestions for candidate companies appreciated.

TC: 400k
ML Eng