Command line to find prime factors up to about 40-digit
echo 1534842682831474675191613986513705075285853096908253230732277917454586669752032261197652469052432398524331417918409196804434169528839 | ecm -n -c 2111 3e6
Command line to find prime factors up to about 45-digit
echo 1534842682831474675191613986513705075285853096908253230732277917454586669752032261197652469052432398524331417918409196804434169528839 | ecm -n -c 4441 11e6
Command line to find prime factors up to about 50-digit
echo 1534842682831474675191613986513705075285853096908253230732277917454586669752032261197652469052432398524331417918409196804434169528839 | ecm -n -c 7548 43e6
Command line to find prime factors up to about 55-digit
echo 1534842682831474675191613986513705075285853096908253230732277917454586669752032261197652469052432398524331417918409196804434169528839 | ecm -n -c 17769 11e7