1980 is the natural number following 1979 and preceding 1981.

Mathematics

1980 is a pronic number,[1] a highly abundant number,[2] an e-perfect number[3] and a coreful perfect number.[4] Not only is it highly abundant, but it also has a greater aliquot sum than any smaller number.[5]

1980 is the fourth number with 36 divisors.[6] It forms an amicable triple with 2016 and 2556, since σ(1980) = σ(2016) = σ(2556) and 6552 = 1980 + 2016 + 2556.[7]

References

  1. ^ Sloane, N. J. A. (ed.). "Sequence A002378 (Oblong (or promic, pronic, or heteromecic) numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  2. ^ Sloane, N. J. A. (ed.). "Sequence A002093 (Highly abundant numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  3. ^ Sloane, N. J. A. (ed.). "Sequence A054979 (e-perfect numbers: numbers k such that the sum of the e-divisors (exponential divisors) of k equals 2*k.)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  4. ^ Sloane, N. J. A. (ed.). "Sequence A307958". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  5. ^ Sloane, N. J. A. (ed.). "Sequence A034090 (Numbers k whose sum of proper divisors exceeds that of all smaller numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  6. ^ Sloane, N. J. A. (ed.). "Sequence A175746 (Numbers with 36 divisors)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  7. ^ Sloane, N. J. A. (ed.). "Sequence A125490". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.


Allikas: https://en.wikipedia.org/wiki/1980_(number)
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