There is a 21mm stone in my right renal. (right renal calculus) can it be cured with medicine?

Not likely: When a stone is bigger than 9mm there is less than a 25% chance of it passing. Yours is significantly larger. Talk to your doctor, based on the type, ultrasound waves to destroy, surgery to remove, or do nothing will likely be your options. Good luck.

Not likely: Is not likely that it 2 cm stone can be cured by any means other than by operative procedure. There are several options. See a urologist.