28 (twenty-eight) is the natural number following 27 and preceding 29.
28 is a composite number, a perfect number, a harmonic divisor number, a centered nonagonal number, a hexagonal number, a happy number, and a triangular number.
28 also appears in the Padovan sequence.
In algebraic geometry, 28 is the number of bitangents to a general plane quartic curve.
In science 28 is the fourth magic number in physics. It is also the atomic number of the element Nickel.
References
External links Prime Curios! 28 from the Prime Pages