2129

This number is a prime.

+ The smallest Sophie Germain prime that is also a strong prime with digits that alternate in parity.

2129 is the smallest Sophie Germain prime that is also a twin prime with digits that alternate in parity.

2129, when concatenated with the next 2 primes, is prime: 212921312137 is prime. [Noll]

+ The next prime year that is the sum of three consecutive primes.

+ The smallest prime Q=2129 that produces 10 primes from the formula pi#+Q#/pi#, for i=30, 92, 95, 161, 163, 164, 169, 278, 295 and 307. No other primorial is known that produces more than 10 primes. Found by Jan van Delden. [Rivera]

(There are 2 curios for this number that have not yet been approved by an editor.)

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