Int32.MinValue, champ

long[] numbersToConvert = { 162345, 32183, -54000, Int64.MaxValue/2 };
int newNumber;
foreach (long number in numbersToConvert)
{
   if (number >= Int32.MinValue && number <= Int32.MaxValue)
   {
      newNumber = Convert.ToInt32(number);
      Console.WriteLine("Successfully converted {0} to an Int32.", 
                        newNumber);
   }
   else
   {
      Console.WriteLine("Unable to convert {0} to an Int32.", number);
   }
}
// The example displays the following output to the console:
//    Successfully converted 162345 to an Int32.
//    Successfully converted 32183 to an Int32.
//    Successfully converted -54000 to an Int32.
//    Unable to convert 4611686018427387903 to an Int32.