Command line to find prime factors up to about 20-digit
echo 2916768192185476209130600299020222703251001859873551312550186038537008789362831619096830736907690865140108164330933656050977865580289 | ecm -n -c 74 11e3
Command line to find prime factors up to about 25-digit
echo 2916768192185476209130600299020222703251001859873551312550186038537008789362831619096830736907690865140108164330933656050977865580289 | ecm -n -c 214 5e4
Command line to find prime factors up to about 30-digit
echo 2916768192185476209130600299020222703251001859873551312550186038537008789362831619096830736907690865140108164330933656050977865580289 | ecm -n -c 430 25e4
Command line to find prime factors up to about 35-digit
echo 2916768192185476209130600299020222703251001859873551312550186038537008789362831619096830736907690865140108164330933656050977865580289 | ecm -n -c 904 1e6
Command line to find prime factors up to about 40-digit
echo 2916768192185476209130600299020222703251001859873551312550186038537008789362831619096830736907690865140108164330933656050977865580289 | ecm -n -c 2350 3e6