Prime Curios!: 169

169
(another Prime Pages' Curiosity)

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169 = (2⁷ + 7²) - (7 + 1) and is the smallest perfect square of the form (2^p + p²) - (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]

(There is one curio for this number that has not yet been approved by an editor.)