Command line to find prime factors up to about 25-digit
echo 4245559892095180107490648708323319773067233665982611447074934022526722994953255169332732599280091072135423316555671991956315456055025317046504919661585664088280996608262261 | ecm -n -c 204 5e4
Command line to find prime factors up to about 30-digit
echo 4245559892095180107490648708323319773067233665982611447074934022526722994953255169332732599280091072135423316555671991956315456055025317046504919661585664088280996608262261 | ecm -n -c 430 25e4
Command line to find prime factors up to about 35-digit
echo 4245559892095180107490648708323319773067233665982611447074934022526722994953255169332732599280091072135423316555671991956315456055025317046504919661585664088280996608262261 | ecm -n -c 904 1e6
Command line to find prime factors up to about 40-digit
echo 4245559892095180107490648708323319773067233665982611447074934022526722994953255169332732599280091072135423316555671991956315456055025317046504919661585664088280996608262261 | ecm -n -c 2350 3e6