Command line to find prime factors up to about 20-digit
echo 6338095311422806628041681278497479626715196088761396462118763294477096960206884824639260108850297771297395071653505161859348368210705651421925743791 | ecm -n -c 74 11e3
Command line to find prime factors up to about 25-digit
echo 6338095311422806628041681278497479626715196088761396462118763294477096960206884824639260108850297771297395071653505161859348368210705651421925743791 | ecm -n -c 214 5e4
Command line to find prime factors up to about 30-digit
echo 6338095311422806628041681278497479626715196088761396462118763294477096960206884824639260108850297771297395071653505161859348368210705651421925743791 | ecm -n -c 430 25e4
Command line to find prime factors up to about 35-digit
echo 6338095311422806628041681278497479626715196088761396462118763294477096960206884824639260108850297771297395071653505161859348368210705651421925743791 | ecm -n -c 904 1e6
Command line to find prime factors up to about 40-digit
echo 6338095311422806628041681278497479626715196088761396462118763294477096960206884824639260108850297771297395071653505161859348368210705651421925743791 | ecm -n -c 2350 3e6