19

This number is a prime.

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

+ If p, q, r, s are consecutive prime numbers such that p > q > r > s > 19, then floor((p * q)/(r * s)) = 1. [Capelle]

+ There are exactly 19 primes beginning with the digit 2 among primes smaller than one thousand. [Capelle]

+ The smallest multidigit number (coincidentally prime) that does not form a palindrome when added to its reversal. [Capelle]

+ Farideh Firoozbakht improved the Papadimitriou's conjecture and proposed that every prime number p greater than or equal to 19 can be written as p = 2q + 3r, where q and r are odd primes. [Capelle]

+ The largest natural number n for which the sum of digits is not smaller than n/2. [Capelle]

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