Command line to find prime factors up to about 35-digit
echo 991702798207816100954140433867447427568618911920738412315302224850630435656823482780611952845279892587218789800109600145919242116610358648356725231435988982387580834579308926542432803 | ecm -n -c 825 1e6
Command line to find prime factors up to about 40-digit
echo 991702798207816100954140433867447427568618911920738412315302224850630435656823482780611952845279892587218789800109600145919242116610358648356725231435988982387580834579308926542432803 | ecm -n -c 2336 3e6
Command line to find prime factors up to about 45-digit
echo 991702798207816100954140433867447427568618911920738412315302224850630435656823482780611952845279892587218789800109600145919242116610358648356725231435988982387580834579308926542432803 | ecm -n -c 4479 11e6
Command line to find prime factors up to about 50-digit
echo 991702798207816100954140433867447427568618911920738412315302224850630435656823482780611952845279892587218789800109600145919242116610358648356725231435988982387580834579308926542432803 | ecm -n -c 7553 43e6