9921

This number is a composite.

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The largest four-digit composite number ending in 1, 3, 7, or 9 that yields no primes if the first digit is changed. I.e., 1921, 2921, 3921, 4921, 5921, 6921, 7921 and 8921 are all composite numbers

Submitted: 2004-01-01 06:11:44; Last Modified: 2008-01-30 17:28:00.