Seventy-eight

Seventy-eight (78, LXXVIII) is the natural number following seventy-seven and followed by seventy-nine. It is a triangular number as well as a composite number, with its divisors being 1, 2, 3, 6, 13, 26, 39 and 78, and its factorization:

makes it a sphenic number.

78 is also:

The atomic number of platinum.
The designation of Interstate 78, a freeway that runs from Pennsylvania to New York.
Karl A. Dahlke proved in 1989 that 78 heptominoss of this shape ( ), at a minimum, must be used in order to fill a rectangle.
In reference to analogue disc records, 78 refers those meant to be spun at 78 revolutions per minute. Compare: LP, 33 and 45.
A standard Tarot deck containing the 22 cards of the major arcana (including the fool) and the 56 cards of the minor arcana make up 78 cards.