Goodbye to 2017, a Prime, Sexy, Odious Year
For a math geek like me, the properties of numbers are a source of excitement and fun. In that spirit, it’s a joy to point out that 2,017 is a prime number — that is, an integer only divisible by 1 and by itself. 1
And it’s not just any prime. It’s half of what mathematicians call a “sexy prime pair.” Before you get any abnormal impressions of mathematicians, I should clarify: Here, “sexy” comes from “sexa,” the Latin root for “six.” The term means that 2,017 is separated from another prime, in this case 2,011, by exactly 6. 2
That’s not all. If we multiply 2,017 by pi — the ancient constant that equals the circumference of a circle divided by its diameter — and then round to the nearest integer, we get another prime number: 6,337. We also get a prime if we start with 2,017 and tack on every decimal digit at the end to get 20,170,123,456,789.
It’s possible to cut a pizza into 2,017 slices using only 63 straight cuts across the whole pie. And if we convert 2,017 to its binary equivalent made up only of zeros and ones — 11111100001 — it becomes what mathematicians call odious. 3
So what should we expect from 2018? Next year isn't a prime number, but it’s about as close as you can get: 2,018 only has two factors — it’s 2 times 1,009. That makes it semiprime, not to be confused with subprime (a type of loan). And 2,018 is also a prime-part-partition number, but that’s a story for next December.
In the meantime, I hope you enjoyed your prime time while you had it. The next prime year after 2017 is 2027, a decade away. Hmm, now add 2 + 0 + 1 + 7 to 2,017 and see what you get.
Happy New Year x 10!
And indeed, 2,011 = 2,017 + (2 - 0 - 1 - 7).
That’s not mathematical social commentary – it just means that the binary expansion has an odd number of ones.
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Jonathan Landman at firstname.lastname@example.org