1,111,111,111

Number
$1 \, 111 \, 111 \, 111$ is:


 * $11 \times 41 \times 271 \times 9091$


 * The $n$th Kaprekar number after $1, 9, 45, 55, 99, 297, \ldots, 38962, 77 \, 778, 82 \, 656, 95 \, 121, 99 \, 999, \ldots$:
 * $1 \, 111 \, 111 \, 111^2 = 1 \, 234 \, 567 \, 900 \, 987 \, 654 \, 321 \to 123 \, 456 \, 790 + 0 \, 987 \, 654 \, 321 = 1 \, 111 \, 111 \, 111$