Command line to find prime factors up to about 20-digit
echo 550336101268352742564175065850917931481205184392555598091471053185697161080095645688402284757417068791897730021611279524144412805156235122623724053442449406480212673871521921483484409611 | ecm -n -c 74 11e3
Command line to find prime factors up to about 25-digit
echo 550336101268352742564175065850917931481205184392555598091471053185697161080095645688402284757417068791897730021611279524144412805156235122623724053442449406480212673871521921483484409611 | ecm -n -c 214 5e4
Command line to find prime factors up to about 30-digit
echo 550336101268352742564175065850917931481205184392555598091471053185697161080095645688402284757417068791897730021611279524144412805156235122623724053442449406480212673871521921483484409611 | ecm -n -c 430 25e4
Command line to find prime factors up to about 35-digit
echo 550336101268352742564175065850917931481205184392555598091471053185697161080095645688402284757417068791897730021611279524144412805156235122623724053442449406480212673871521921483484409611 | ecm -n -c 904 1e6
Command line to find prime factors up to about 40-digit
echo 550336101268352742564175065850917931481205184392555598091471053185697161080095645688402284757417068791897730021611279524144412805156235122623724053442449406480212673871521921483484409611 | ecm -n -c 2350 3e6