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|Factorization||2 · 3 · 13|
|Divisors||1, 2, 3, 6, 13, 26, 39, 78|
78 is the 12th triangular number.
77 and 78 form a Ruth-Aaron pair.
Since it is possible to find sequences of 78 consecutive integers such that each inner member shares a factor with either the first or the last member, 78 is an Erdős–Woods number.
In other fields
78 is also:
- In reference to gramophone records, 78 refers those meant to be spun at 78 revolutions per minute. Compare: LP, 33 1/3 and 45 rpm. 33+45=78
- A typical tarot deck containing the 21 trump cards, the Fool and the 56 suit cards make up 78 cards
- The total number of gifts in the song The Twelve Days of Christmas (since 78 is the 12th triangular number)
- The number of lines that make up Metatron's Cube
- The Rule of 78s is a method of yearly interest calculation
- Municipal Okrug 78, a municipal okrug of Tsentralny District of St. Petersburg, Russia