How many Centers are there in ISRO & where are these centers are located? What is the major function of these Centers?

So what I know is that there are 21 centers in ISRO across India. There major function are this as I studied, Manufacturing satellites, developing launch vehicles or even tracking them once they have been launched into orbit around Earth or beyond. Here I am sharing the link for better experience.

So talking about there locations I am sharing here with you..

Bengaluru, Dehradun, Thiruvananthapuram, Mahendragiri, Hassan, Hyderabad, Nellore, Ahmedabad.. 

These are some locations but remainder most of them are in Bengaluru and Thiruvananthapuram. You can check the list of centers I have pasted above……