In Mathematics
- 181 is an odd number
- 181 is a centered number
- 181 is a centered pentagonal number
- 181 is a centered 12-gonal number
- 181 is a centered 18-gonal number
- 181 is a centered 30-gonal number
- 181 is a centered square number
- 181 is a star number that represents a centered hexagram (as in the game of Chinese checkers)
- 181 is a deficient number, as 1 is less than 181
- 181 is an odious number
- 181 is a prime number
- 181 is a Chen prime
- 181 is a dihedral prime
- 181 is a full reptend prime
- 181 is a palindromic prime
- 181 is a strobogrammatic prime, the same when viewed upside down
- 181 is a twin prime with 179
- 181 is a square-free number
- 181 is an undulating number, if written in the ternary, the negaternary, or the nonary numeral systems
- 181 is the difference of 2 square numbers: 912 – 902
- 181 is the sum of 2 consecutive square numbers: 92 + 102
- 181 is the sum of 5 consecutive prime numbers: 29 + 31 + 37 + 41 + 43
Read more about this topic: 181 (number)
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