Twenty-eight (28) is a positive integer one more than 27 one less than 29.

## Properties Edit

28 is an even composite number.

28 is the 7th triangular number, and therefore the number of tiles in a double-six domino set.

28 is the 4th hexagonal number.

28 is equal to 7!!!, the triple factorial of 7.

28 is equal to the sum of its proper divisors: 1 + 2 + 4 + 7 + 14 = 28. This makes it a perfect number, the neighboring ones being 6 and 496. Ignoring Easter, the Julian calendar repeats every**28**years.

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