Command line to find prime factors up to about 20-digit
echo 6644733876747052811348142304063686673332811352572126648184708540376780774835772633597081278495525934562439290665799012083116318170678184796029372824611031122050804084783703391483245248157 | ecm -n -c 74 11e3
Command line to find prime factors up to about 25-digit
echo 6644733876747052811348142304063686673332811352572126648184708540376780774835772633597081278495525934562439290665799012083116318170678184796029372824611031122050804084783703391483245248157 | ecm -n -c 214 5e4
Command line to find prime factors up to about 30-digit
echo 6644733876747052811348142304063686673332811352572126648184708540376780774835772633597081278495525934562439290665799012083116318170678184796029372824611031122050804084783703391483245248157 | ecm -n -c 430 25e4
Command line to find prime factors up to about 35-digit
echo 6644733876747052811348142304063686673332811352572126648184708540376780774835772633597081278495525934562439290665799012083116318170678184796029372824611031122050804084783703391483245248157 | ecm -n -c 904 1e6
Command line to find prime factors up to about 40-digit
echo 6644733876747052811348142304063686673332811352572126648184708540376780774835772633597081278495525934562439290665799012083116318170678184796029372824611031122050804084783703391483245248157 | ecm -n -c 2350 3e6