2016 (number)

From HandWiki
Short description: Hardy-Ramanujan number
Short description: Natural number
← 2015 2016 2017 →
Cardinaltwo thousand sixteen
Ordinal2016th
(two thousand sixteenth)
Factorization25 × 32 × 7
Divisors1, 2, 3, 4, 6, 7, 8, 9, 12, 14, 16, 18, 21, 24, 28, 32, 36, 42, 48, 56, 63, 72, 84, 96, 112, 126, 144, 168, 224, 252, 288, 336, 504, 672, 1008, 2016
Greek numeral,ΒΙϚ´
Roman numeralMMXVI
Binary111111000002
Ternary22022003
Quaternary1332004
Quinary310315
Senary132006
Octal37408
Duodecimal120012
Hexadecimal7E016
Vigesimal50G20
Base 361K036

2016 is the natural number following 2015 and preceding 2017.

In mathematics

  • 2016 is a triangular number, being 1 + 2 + 3 + ... + 63. Equivalently, [math]\displaystyle{ \tbinom{64}{2} = 2016 }[/math].
  • 2016 is a 24-gonal number (sequence A051876 in the OEIS) and a generalized 28-gonal (icosioctagonal) number (sequence A303812 in the OEIS).
  • 2016 has 36 divisors.
  • 211 − 25 = 2016.
  • 2016 forms a friendly pair with 360, as [math]\displaystyle{ \dfrac{\sigma(360)}{360} = \dfrac{1170}{360} = \dfrac{13}{4} = 3.25 }[/math] and [math]\displaystyle{ \dfrac{\sigma(2016)}{2016} = \dfrac{6552}{2016} = \dfrac{13}{4} = 3.25 }[/math]. 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 (sequence A001262 in the OEIS). 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 (sequence A194472 in the OEIS) because, while not perfect, 2016 is the sum of its first 31 divisors (up to and including 288).
  • 2016 × 20 = 40,320 = [math]\displaystyle{ 8! }[/math] (read as "8 factorial").
  • [math]\displaystyle{ {{2016^{17}+1}\over 2017} }[/math] is prime. Since 2017 is similarly prime, 201617 + 1 is a semiprime. (sequence A104494 in the OEIS)