Command line to find prime factors up to about 20-digit
echo 6338577656753306389638288038296478258138443424665633039591550976964948978986424554633090099010628370660221278462022331222827989924461242896132198564559 | ecm -n -c 74 11e3
Command line to find prime factors up to about 25-digit
echo 6338577656753306389638288038296478258138443424665633039591550976964948978986424554633090099010628370660221278462022331222827989924461242896132198564559 | ecm -n -c 214 5e4
Command line to find prime factors up to about 30-digit
echo 6338577656753306389638288038296478258138443424665633039591550976964948978986424554633090099010628370660221278462022331222827989924461242896132198564559 | ecm -n -c 430 25e4
Command line to find prime factors up to about 35-digit
echo 6338577656753306389638288038296478258138443424665633039591550976964948978986424554633090099010628370660221278462022331222827989924461242896132198564559 | ecm -n -c 904 1e6
Command line to find prime factors up to about 40-digit
echo 6338577656753306389638288038296478258138443424665633039591550976964948978986424554633090099010628370660221278462022331222827989924461242896132198564559 | ecm -n -c 2350 3e6