Hello Manjunath ,
Welcome to HealthcareMagic forum.
Yes it's normal for toddlers ( around or near 2 years)to touch and explore their genitals ( masturbate) many times a day .
This is a phase and will soon resolve on its own unless becoming a hard tot break habbit.
Simple irritation or pain won't cause this and infact one third of normal children have this habbit .
But if there is any crying , pain during urination or fever
etc then it might suggest Urinary infection.
Try the following for decreasing it,
1.Do not scold or restrict him or tell him it's sin or bad. Try to ignore and distract instead.
2.when in public you can gently remind him good manners like , “Some things are private. You can do that at home in your room— how about playing with this toy for now?”
3.See if they do it due to boredom or want of comfort .
4. It's best to consult a pediatrician
if the child continues it as a habbit even after completion of three years.
Hope this answer is helpful to you .