Strobogrammatic number

The number 619 is strobogrammatic.

A strobogrammatic number is a number whose numeral is rotationally symmetric, so that it appears the same when rotated 180 degrees.[1] In other words, the numeral looks the same right-side up and upside down (e.g., 69, 96, 1001).[2] A strobogrammatic prime is a strobogrammatic number that is also a prime number, i.e., a number that is only divisible by one and itself (e.g., 11).[3] It is a type of ambigram, words and numbers that retain their meaning when viewed from a different perspective, such as palindromes.[4]

  1. ^ "Strobogrammatic number". Encyclopædia Britannica. Archived from the original on 21 September 2021. Retrieved 19 September 2021.
  2. ^ Schaaf, William L. (1 March 2016) [1999]. "Number game". Encyclopedia Britannica. Archived from the original on 2 February 2017. Retrieved 22 January 2017.
  3. ^ Caldwell, Chris K. "The Prime Glossary: strobogrammatic". primes.utm.edu. Archived from the original on 8 January 2017. Retrieved 22 January 2017.
  4. ^ Sloane, N. J. A. (ed.). "Sequence A000787 (Strobogrammatic numbers: the same upside down)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 22 January 2017.