Command line to find prime factors up to about 20-digit
echo 837680816588894176485735115978051985632321886091628452926325226397687717499064407103944955595571984434969033396365960906140242191859597618887027294350900173838052227170486339651 | ecm -n -c 74 11e3
Command line to find prime factors up to about 25-digit
echo 837680816588894176485735115978051985632321886091628452926325226397687717499064407103944955595571984434969033396365960906140242191859597618887027294350900173838052227170486339651 | ecm -n -c 214 5e4
Command line to find prime factors up to about 30-digit
echo 837680816588894176485735115978051985632321886091628452926325226397687717499064407103944955595571984434969033396365960906140242191859597618887027294350900173838052227170486339651 | ecm -n -c 430 25e4
Command line to find prime factors up to about 35-digit
echo 837680816588894176485735115978051985632321886091628452926325226397687717499064407103944955595571984434969033396365960906140242191859597618887027294350900173838052227170486339651 | ecm -n -c 904 1e6
Command line to find prime factors up to about 40-digit
echo 837680816588894176485735115978051985632321886091628452926325226397687717499064407103944955595571984434969033396365960906140242191859597618887027294350900173838052227170486339651 | ecm -n -c 2350 3e6