# 169 (number)

169 (one hundred [and] sixty-nine) is the natural number following 168 and preceding 170.

 ← 168 169 170 →
Cardinalone hundred sixty-nine
Ordinal169th
(one hundred sixty-ninth)
Factorization132
Divisors1, 13, 169
Greek numeralΡΞΘ´
Roman numeralCLXIX
Binary101010012
Ternary200213
Senary4416
Octal2518
Duodecimal12112

## In mathematics

169 is an odd number, a composite number, and a deficient number.

169 is a square number: 13 × 13 = 169, and if each number is reversed the equation is still true: 31 × 31 = 961. 144 shares this property: 12 × 12 = 144, 21 × 21 = 441.

169 is one of the few squares to also be a centered hexagonal number.[1] 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. 169 is a difference in consecutive cubes, equaling ${\displaystyle 8^{3}-7^{3}.}$