Pampena's Prime

Pampena's Prime is equivalent to [math] 10^506-10^253-1 [/math]. It is a a special type of prime number such that the entire prime is is formed with a concatenation of the same digit, save for a different digit in the middle of the number. It has gained notoriety due to the fact it was mentioned in a Numberphile video by mathematician Simon Pampena.

Approximate Size
Pampena's Prime is almost equal in size to one hundred censeptensexagintillion, or roughly a Googol to the fifth power. In order to comprehend the scope of this number, one must construct a fifth dimensional hyper-cube such that each side has a Googol smaller hyper-cubes, then multiply this construction by a Million.