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+ A number that can be expressed as the signed sum of cubes in at least three ways: 2644883 + 3315743 - 3801933 = 23224043 - 8694183 - 22810573 = 4029063 - 2114023 - 3824893. [Rupinski]

+ The smallest prime such that another prime is never produced by inserting the same digit between each pair of its digits (40309, 41319, 42329, ... , 49399, are all composite). [Noll]

+ Take the sum of emirp 439 and its reversal: 439 + 934 = 1373. If we split 1373 in half and factor, we get 13*73 = 949 = 227+722 (a prime and its reversal). Note that 439+722 = 1161 = 934+227 uses each of the above primes and their reversals. [Bergot]

(There are 6 curios for this number that have not yet been approved by an editor.)




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