Command line to find prime factors up to about 45-digit
echo 138940060255352917497510962318998533818910635413057695065614809172817655873731032561767948732767643562656642737775501722271172720487 | ecm -n -c 3962 11e6
Command line to find prime factors up to about 50-digit
echo 138940060255352917497510962318998533818910635413057695065614809172817655873731032561767948732767643562656642737775501722271172720487 | ecm -n -c 7465 43e6
Command line to find prime factors up to about 55-digit
echo 138940060255352917497510962318998533818910635413057695065614809172817655873731032561767948732767643562656642737775501722271172720487 | ecm -n -c 17751 11e7
Command line to find prime factors up to about 60-digit
echo 138940060255352917497510962318998533818910635413057695065614809172817655873731032561767948732767643562656642737775501722271172720487 | ecm -n -c 42014 26e7