This number is a composite.

+ 656601 is the smallest Smith number which is also a Carmichael number. [Gupta]

+ 656601 is the smallest Carmichael number n surrounded by a prime triplet (n-4, n-2, n+2 are all primes). [Yosei]

+ The smallest integer pseudoprime to base-5 that is the midpoint of a cousin prime pair {656599, 656603}. [Bajpai]

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