1111111111111111111111
This number is a composite.
11 1111111111 1111111111
The smallest repunit whose prime factors contain all digits from 0 to 9 (1111111111111111111111 = 11*11*23*4093*8779*21649*513239). [Gupta]
(There is one curio for this number that has not yet been approved by an editor.)
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