In Mathematics
169 is an odd number, a composite number, and a deficient number. 169 is a square number: 13 x 13 = 169, and the if each number is reversed the equation is still true: 31 x 31 = 961.
169 is one of the few squares to also be a centered hexagonal number. Like all odd squares, it is a centered octagonal number. 169 is an odd-indexed Pell number, thus it is also a Markov number, appearing in the solutions (2, 169, 985), (2, 29, 169), (29, 169, 14701), etc. 169 is the sum of seven consecutive primes: 13 + 17 + 19 + 23 + 29 + 31 + 37.
Read more about this topic: 169 (number)
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