Command line to find prime factors up to about 35-digit
echo 11554613916214894281021574521910233331634605437866495372633478923589449330504805570992274605527460343745462667293341535069898598599392844614255642097741759262778911748212958390087976900537 | ecm -n -c 786 1e6
Command line to find prime factors up to about 40-digit
echo 11554613916214894281021574521910233331634605437866495372633478923589449330504805570992274605527460343745462667293341535069898598599392844614255642097741759262778911748212958390087976900537 | ecm -n -c 2318 3e6
Command line to find prime factors up to about 45-digit
echo 11554613916214894281021574521910233331634605437866495372633478923589449330504805570992274605527460343745462667293341535069898598599392844614255642097741759262778911748212958390087976900537 | ecm -n -c 4475 11e6
Command line to find prime factors up to about 50-digit
echo 11554613916214894281021574521910233331634605437866495372633478923589449330504805570992274605527460343745462667293341535069898598599392844614255642097741759262778911748212958390087976900537 | ecm -n -c 7553 43e6