Command line to find prime factors up to about 20-digit
echo 529856106264891531274975921946185220674983429581692985789352046598898915504374018475945702340574591419521591611266718959758533263469297942680973085220272763 | ecm -n -c 74 11e3
Command line to find prime factors up to about 25-digit
echo 529856106264891531274975921946185220674983429581692985789352046598898915504374018475945702340574591419521591611266718959758533263469297942680973085220272763 | ecm -n -c 214 5e4
Command line to find prime factors up to about 30-digit
echo 529856106264891531274975921946185220674983429581692985789352046598898915504374018475945702340574591419521591611266718959758533263469297942680973085220272763 | ecm -n -c 430 25e4
Command line to find prime factors up to about 35-digit
echo 529856106264891531274975921946185220674983429581692985789352046598898915504374018475945702340574591419521591611266718959758533263469297942680973085220272763 | ecm -n -c 904 1e6
Command line to find prime factors up to about 40-digit
echo 529856106264891531274975921946185220674983429581692985789352046598898915504374018475945702340574591419521591611266718959758533263469297942680973085220272763 | ecm -n -c 2350 3e6