9

Just showing those entries submitted by 'Silva': (Click here to show all)

+ 9^8 + 8^7 + 7^6 + 6^5 + 5^4 + 4^3 + 3^2 + 2^1 + 1^0 is prime. [Silva]

+ The first digit to appear as an end-digit in two consecutive primes (139 and 149). [Silva]

+ The only composite digit that can appear as end-digit of a prime. [Silva]

+ The only non-prime digit that is the difference of consecutive squares. [Silva]

+ 9+8^7+6^5+4^3+2^1 is prime. [Silva]

(There are 3 curios for this number that have not yet been approved by an editor.)

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