Command line to find prime factors up to about 45-digit
echo 15577662994010806695081485383292865818538910442711407635938972466437913133193751103661177414020434422659176947550508383832976269546051 | ecm -n -c 3962 11e6
Command line to find prime factors up to about 50-digit
echo 15577662994010806695081485383292865818538910442711407635938972466437913133193751103661177414020434422659176947550508383832976269546051 | ecm -n -c 7465 43e6
Command line to find prime factors up to about 55-digit
echo 15577662994010806695081485383292865818538910442711407635938972466437913133193751103661177414020434422659176947550508383832976269546051 | ecm -n -c 17751 11e7
Command line to find prime factors up to about 60-digit
echo 15577662994010806695081485383292865818538910442711407635938972466437913133193751103661177414020434422659176947550508383832976269546051 | ecm -n -c 42014 26e7