-Your character level.
-Your character cash.
-Your treasure items.
-Your fame points.
-Your total crime completion % (The higher, the better)
The exact equation is secret.
Every treasure item gives different power. Some even give negative while
there are some which give random amounts of power, depending on various
factors.
Finally, fame points give some bonus power which is relevant to your base
power (level,cash,treasure items) and is generally not that big. Fame points
bonus is also relevant to the amount of fame points you have but there is a
limit to 500 fame points; No fame point above 500 give any bonus.