Prime Number Formed by Concatenating Consecutive Integers down to 1

Theorem
Let $N$ be an integer whose decimal representation consists of the concatenation of all the integers from a given $n$ in descending order down to $1$.

Let the $N$ that is so formed be prime.

The only $n$ less than $100$ for which this is true is $82$.

That is:
 * $82 \, 818 \, 079 \, 787 \, 776 \ldots 121 \, 110 \, 987 \, 654 \, 321$

is the only prime number formed this way starting at $100$ or less.

Proof
Can be determined by checking all numbers formed in such a way for primality.