Command line to find prime factors up to about 20-digit
echo 1224390947522050424013569216107991230853452870184672956082444918280798828888583758842477428430906088427902244576837348330552065411836521 | ecm -n -c 74 11e3
Command line to find prime factors up to about 25-digit
echo 1224390947522050424013569216107991230853452870184672956082444918280798828888583758842477428430906088427902244576837348330552065411836521 | ecm -n -c 214 5e4
Command line to find prime factors up to about 30-digit
echo 1224390947522050424013569216107991230853452870184672956082444918280798828888583758842477428430906088427902244576837348330552065411836521 | ecm -n -c 430 25e4
Command line to find prime factors up to about 35-digit
echo 1224390947522050424013569216107991230853452870184672956082444918280798828888583758842477428430906088427902244576837348330552065411836521 | ecm -n -c 904 1e6
Command line to find prime factors up to about 40-digit
echo 1224390947522050424013569216107991230853452870184672956082444918280798828888583758842477428430906088427902244576837348330552065411836521 | ecm -n -c 2350 3e6