xxxxxxxxxx
use Illuminate\Support\Str;
// ...
public function generateUniqueNumber()
{
$uuid = Str::uuid();
// Remove hyphens to get a 32-character alphanumeric string
$uuidWithoutHyphens = str_replace('-', '', $uuid);
// Take the first 16 characters to get a 16-digit number
$uniqueNumber = substr($uuidWithoutHyphens, 0, 16);
return $uniqueNumber;
}