987
This number is a composite.
987 is the only 3-digit number with consecutively decreasing digits such that when multiplied by the sum of its digits plus and minus one, the results are primes.
I.e., 987*(9+8+7)-1 and 987*(9+8+7)+1 are primes. [Opao]
(There are 2 curios for this number that have not yet been approved by an editor.)
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