78 (seventy-eight) is the natural number following 77 and followed by 79.
78 is a triangular number, and its factorization makes it a sphenic number. As a multiple of a perfect number, 78 is itself a semiperfect number.
77 and 78 form a Ruth-Aaron pair under the second definition in which repeated prime factors are counted as often as they occur.
Since it is possible to find sequences of 78 consecutive integers such that each inner member shares ...
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