The book is now available! 647
(another Prime Pages' Curiosity)
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+ The smallest prime that may be written as 2a2 - 1, and also as 3b3 - 1. [Hartley]

+ A man described as looking like a plump Moses asked the following questions during a 1987 joint American Mathematical Society/Mathematical Association of America conference in San Antonio, Texas: "What about 647? Is it prime?" (from The Man Who Loved Only Numbers by Paul Hoffman)

+ 647 equals the sum of all two-digit even semiprimes plus one. [Silva]

+ The largest prime with prime perimeter whose digits form an acute-angle scalene triangle. [Loungrides]

(There are 2 curios for this number that have not yet been approved by an editor.)




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