2016 (number)

2016 is the natural number following 2015 and preceding 2017.

In mathematics

* 2016 is a triangular number, being 1 + 2 + 3 + ... + 63. Equivalently, $\tbinom = 2016$.
* 2016 is a 24-gonal number and a generalized 28-gonal (icosioctagonal) number .
* 2016 has 36 divisors.
* 2¹¹ − 2⁵ = 2016.
* 2016 forms a friendly pair with 360, as $\dfrac = \dfrac = \dfrac = 3.25$ and $\dfrac = \dfrac = \dfrac = 3.25$. The number 360 itself is a highly composite number, while 2016, while not highly composite, is highly composite among the positive integers not divisible by five.
* 2016 × 2 + 1 = 4033. Although 4033 is not prime, as 4033 = 37 × 109, it is a strong pseudoprime to base 2 . Aside from 2016, the only other numbers below 10,000 with this property are 1023, 1638, 2340, 4160, and 7920.
* There are 2016 five-cubes in a nine-cube.
* 2016 is an Erdős–Nicolas number because, while not perfect, 2016 is the sum of its first 31 divisors (up to and including 288).
* 2016 × 20 = 40,320 = $8!$ (read as "8 factorial").
* $$ is prime. Since 2017 is similarly prime, 2016¹⁷ + 1 is a semiprime.

In other fields

* 2016 is the number of blocks that occur approximately every two weeks in Bitcoin before a difficulty adjustment is made.

References

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Integers