This number is a composite.

+ The number obtained by concatenating the first prime and twice the next prime. [Russo]

+ The prime factorization of 26 uses the first three counting numbers. [Trotter]

+ One of only two numbers which contain exactly the first three digits in its unique prime factorization. [Hunter]

+ The number of minimal primes which cover the set of primes in base 10. [Rupinski]

+ 26 is the smallest number that can be expressed by three identical prime digits in a prime base, i.e., 222 in base three. Note that it is also the reverse of the second such number: 62 = 222 in base 5. [Necula]

+ 26 = 2 * prime(6). [Gupta]

+ There are no twin primes between 262 and 282. [Wesolowski]

+ The only number n < 1000 such that 10^n plus or minus 123456789 are both primes. [Loungrides]

+ The largest of three successive numbers n, n-1, n-2 such that the product of each of them with its reversal plus 1 is prime, i.e., 26*62+1=1613, 25*52+1=1301, 24*42+1=1009. [Loungrides]

+ The number of primes that end in 3 among the first 100 primes. A greater number than endings 1, 7, or 9. [Honaker]

(There are 7 curios for this number that have not yet been approved by an editor.)

Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell