What is a noun for prosper?

There isn't a single perfect noun for "prosper." However, depending on the context, you could use several options:

General prosperity:

* Prosperity itself can function as a noun.

* Success

* Flourishing

* Thriving

* Booming

* Growth

Specific types of prosperity:

* Wealth (financial prosperity)

* Well-being (general prosperity)

* Progress (improvement over time)

* Advancement (moving forward)

The best word to use depends on the specific meaning you want to convey.