according to wikipedia, there are about 10⁸⁰ protons in the observable universe

you would need 266 bits to give each one a different number
if you are using base 64, you would need 45 digits
it would look something like this aGVoc3Z4ZnN5YWhkYiByaHNqc2hyIGcgZGhzaGVkaGJz1