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169 = (2^{7} + 7^{2})  (7 + 1) and is the smallest perfect square of the form
(2^{p} + p^{2})  (p + 1). [Charles]
The smallest square that is prime when turned upside down. [Wu] 169 is the first composite Pell number with a prime index. Coincidentally, it is also the last square in the Pell sequence. [Axoy] The sum of first 12 powers of semiprimes is (12+1)^2. [Post] The sum of first five emirps can be represented as the square of the first emirp. [Loungrides]
(There are 4 curios for this number that have not yet been approved by an editor.)
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