This number is a composite.

+ The only base-2 pseudoprime formed entirely from Fermat primes (17*257).

+ Smaller of the only known base-2 twin pseudoprime. [Gupta]

+ The smallest base-2 pseudoprime that is a hexadecimal repunit: R4 = 0x1111. The second is R7, and by concatenating them, one has the third, R11. [Yosei]

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