Answers for "php set to minimum number possible"

php int min

PHP_INT_MAX (int) // The largest integer supported in this build of PHP. 
  
PHP_INT_MIN (int) // The smallest integer supported in this build of PHP.

set a minimum character value in php

if (strlen($input) < 12)
{
   echo "Input is too short, minimum is 12 characters (20 max).";
}
elseif(strlen($input) > 20)
{
   echo "Input is too long, maximum is 20 characters.";
}