135

This number is a composite.

+ The two prime factors of 135 are 3 and 5. Note that, starting with 3, the sum of 5 consecutively squared integers equals 135. [Cramer]

+ Both 1!+3!+5! and 1!!+3!!+5!! are primes. [Jevtic]

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

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