17 (number)
From Halbeeg, the open encyclopedia · Af-Soomaali
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17 is a natural number that lies between 16 and 18. It is written in standard Hindu-Arabic numerals as "17", while in Roman numerals it is written as XVII.
17 is a prime number—meaning that only 1 and 17 divide it evenly. It is the seventh prime number, following 2, 3, 5, 7, 11, and 13. It is also an odd number, since it cannot be divided by 2.
Mathematical properties
17 and 19 form a twin prime pair, since their difference is two. When squared, 17 equals 289; when cubed, it equals 4,913. The sum of its proper divisors (excluding 17 itself) equals 1, making it a prime number in its own right.
One notable property in geometry: a regular polygon with 17 sides (a heptadecagon) can be constructed using only a compass and straightedge. This result is connected to the work of German mathematician Carl Friedrich Gauss and depends on the fact that 17 is a Fermat prime.
Numeral systems
In binary, 17 is written as 10001. In hexadecimal, it is 11. In Somali, it is called "toddoba iyo toban" (seven and ten), based on the pattern of adding ten and seven.
Cultural usage
Numbers like 17 carry different meanings across various cultures; for example, some southern European societies regard the number as unlucky, while in other places it holds neutral significance. These meanings are culturally constructed rather than mathematically derived.