199th day of the year - A very interesting number

For those who follow me on other social media platforms you’ll have seen my musings on why 197 is an interesting number. Well, as it turns out 199 is also an interesting number.

199 is a twin prime (Twinned with the aforementioned 197) Twin primes are prime numbers that are separated from each other by two….Not as exciting as sexy primes but mathematically more challenging!

It is an 'invertible prime.’ If you turn the number upside down it reads 661 which is also a prime number.

It’s also a ‘circular prime.’ It stays a prime number no matter how you arrange its digits (919 and 991 are also prime numbers)

199 is the sum of 3 consecutive primes 61 + 67 + 71 (Incidentally 661 is also the sum of three prime numbers 211 + 223 + 227)….And also the sum of 5 consecutive primes 31 + 37 + 41 + 43 + 47

Aaaaand if you add its digits up the sum is 19 which is also a prime number.

Exciting eh! :-)

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Oh go on then since I didn’t print it here, this is what is interesting about 197

As well as being a prime number 197 is the sum of the first twelve prime numbers: 2 + 3 + 5 + 7 + 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37

197 is also the sum of all digits of all two-digit prime numbers: 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.

Aaaand....197 is the smallest prime number that is the sum of 7 consecutive primes: 17 + 19 + 23 + 29 + 31 + 37 + 41