The problem involves three Pacific island nations, each of which has its own, independent Social Security Administration. The three -- the Federated States of Micronesia, the Republic of the Marshall Islands and the Republic of Palau.
If your U.S. number starts with 002-6, 003-9, 005-7 or 007-8, it could match a number in Micronesia. Numbers that start 006-4 could match numbers in Palau. Those that start with 004 could match numbers in the Marshall Islands.
That works out to roughly 135,000 possible matches
https://www.cleveland.com/nation/index.ssf/2009/08/how_many_americans_social_secu.html https://www.ssa.gov/policy/docs/progdesc/ssptw/2016-2017/asia/ https://www.ssa.gov/policy/docs/progdesc/ssptw/2016-2017/asia/micronesia.html http://www.fsmssa.fm/ https://www.ssa.gov/policy/docs/progdesc/ssptw/2016-2017/asia/marshall-islands.html http://www.rmimissa.org/ https://www.ssa.gov/policy/docs/progdesc/ssptw/2016-2017/asia/palau.html http://www.ropssa.org/