This number is a prime.

+ The roof of Chicago's Willis Tower is 1451 feet above ground level.

+ The other eleven permutations of the digits of 1451 are all semiprimes. [Gaydos]

+ 1451 is the lesser member of a twin prime pair: (1451,1453). Curiously, if we take the sum of digits of both numbers, we also get a twin prime pair. [Anitha]

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