23

This number is a prime.

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

Kristen Eller ©2002
+ The sum of the digits of 23^2+3 is the next prime after 23. [Silva]

+ The sum of the consecutive primes from 23 to the 23rd prime is a palindromic prime. [Silva]

+ 23 + 2*3, 23 + 2^3, and 23 + 2*3 + 2^3 are the three next primes after 23. [Silva]

+ The sum of the prime divisors of its two previous numbers. [Silva]

+ The smallest Sophie Germain prime formed by concatenation of two others. [Silva]

+ The smallest n-digit prime that yields n others if each of its digits is duplicated (223, 233). [Silva]

+ The smallest prime p that divides the reversal of the next prime after p. The next three pairs of consecutive primes of this form and with this property are: 233 239; 2333 2339; 23333 23339. Are there primes of other forms with this property? [Silva]

+ The smallest prime p such that neither p+1 nor p-1 is divisible by the sum of the digits of p. [Silva]

+ 23+2 = (2+3)^2. [Silva]

+ 23 is the only homosexual prime, i.e., a sexy prime which can appear as its own gap: 23 + 2*3 = 29. [Silva]

(There are 24 curios for this number that have not yet been approved by an editor.)

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