10
This number is a composite.
Just showing those entries submitted by 'Silva': (Click here to show all)
10!+9!+8!+ ... +2!+1!+0!+1!+2!+ ... +8!+9!+10! is prime. [Silva]
10+98765432123456789+10 is prime. [Silva]
10^10+9^10+8^10+7^10+6^10+5^10+4^10+3^10+2^10+1^10+2^10+3^10+4^10+5^10+6^10+7^10+8^10+9^10+10^10 is an 11-digit prime. [Silva]
The only even number which can be expressed as the sum of three consecutive primes. [Silva]
10 is the only 1 semiprime with end-digit 0. [Silva]
(There are 18 curios for this number that have not yet been approved by an editor.)
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