270
This number is a composite.
3*270^9-1 and 3*270^9+1 are prime. Note that 270-1 and 270+1 are also primes. [Opao]
270 is the smallest number such that it has divisors ending with every decimal digit, i.e., divisors ending in 0,1,2,3,4,5,6,7,8 and 9. [Gupta]
(There are 3 curios for this number that have not yet been approved by an editor.)
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