I cannot find a serial number that high in any of my Ithaca references. The link below will take you to a good summary of serial numbers for Ithaca shotguns, you may be able to find your model and date there-
You vave an Ithaca sxs Flues model made in 1911
You have an Ithaca sxs Miner model made 1907.
There's a list of serial numbers by year at http://ithacagunrepair.com/page5/page23/
You have an Ithaca Miner model made in 1907 if it is a sxs double not stated in the ques.
You have an Ithaca sxs Flues model made in 1919.
1906
You have an Ithaca Flues model made in 1920 if it is a sxs doubel not stated in your ques.
You have an Ithaca Miner model made in 1907 if it is a sxs double not stated in your ques
You have an Ithaca Baker model made in 1886 if it is a sxs double not stated in your ques
You have an Ithaca Flues model made in 1917 if it is a sxs double not stated in your ques
You have an Ithaca Flues model made in 1917 if it is a sxs double not stated in your ques
You have an Ithaca Flues model made in 1917 if it is a sxs double not stated in your ques.