This number is a prime.

+ π(6521) = 6! + 5! + 2! + 1!. There is only one other prime number with this property. [Honaker]

+ The largest prime from a cyclic permutation on a side of the prime cube, i.e., the unique arrangement (ignoring rotations or reflections) of eight consecutive digits on a cube's vertices such that any two adjacent digits of an edge sum to a prime. [Beedassy]

+ "Project 6521" is a special task force within the Communist Party system established to increase security around sensitive anniversaries.

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