Command line to find prime factors up to about 50-digit
echo 276623909222459955262062365246498315145753233845762190081926880984539629653558336897979021461117054738370602081856376552137256435890922353288561621777151 | ecm -n -c 3866 43e6
Command line to find prime factors up to about 55-digit
echo 276623909222459955262062365246498315145753233845762190081926880984539629653558336897979021461117054738370602081856376552137256435890922353288561621777151 | ecm -n -c 16533 11e7
Command line to find prime factors up to about 60-digit
echo 276623909222459955262062365246498315145753233845762190081926880984539629653558336897979021461117054738370602081856376552137256435890922353288561621777151 | ecm -n -c 41633 26e7
Command line to find prime factors up to about 65-digit
echo 276623909222459955262062365246498315145753233845762190081926880984539629653558336897979021461117054738370602081856376552137256435890922353288561621777151 | ecm -n -c 69332 85e7