Electric potential on circumference of charged ring

[AdityaDev]

I heard that maximum electric potential for charged ring is at its circumference. Is there an expression to find the electric potential at any point on the circumference of a charged ring?

 

[mfb]

A mathematical circle would not have a well-defined surface and also no well-defined potential exactly at the ring.
If the ring has some finite small diameter (so it looks like a donut), it is possible to calculate its potential. I'm not sure if there are analytic formulas for it, but you can certainly get a numerical approximation.