Square Number ending in 9 Digits in Reverse Order

Theorem
The next integer after $1 \, 111 \, 111 \, 111$ whose square ends in $987 \, 654 \, 321$ is:


 * $2 \, 380 \, 642 \, 361^2 = 5 \, 667 \, 458 \, 050 \, 987 \, 654 \, 321$