1980

Previous  ... Next

Number

$1980$ (one thousand, nine hundred and eighty) is:

$2^2 \times 3^2 \times 5 \times 11$


The smallest term of the amicable triplet $\tuple {1980, 2016, 2556}$:
$\map {\sigma_1} {1980} = \map {\sigma_1} {2016} = \map {\sigma_1} {2556} = 6552 = 1980 + 2016 + 2556$


The $2$nd integer after $954$ whose digits are unchanged when subtracting its reversal:
$1980 - 0891 = 1089$


Also see


Sources

  • 1978: Thomas A. Whitelaw: An Introduction to Abstract Algebra ... (previous) ... (next): $\S 13$: The fundamental theorem of arithmetic
  • 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $1980$
  • 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $1980$
This article is issued from ProofWiki. The text is available under Creative Commons Attribution-ShareAlike License unless otherwise noted. Additional terms may apply for the media files.