This number is a prime.
Just showing those entries submitted by 'Silva': (Click here to show all)
The only two-digit prime which is the sum of the digits of all previous two-digit primes. [Silva]
The only two-digit prime whose square is the sum of the squares of two consecutive two-digit numbers: (20^2+21^2). [Silva]
The smallest prime whose sum of the digits and difference of the digits are primes. [Silva]
The next prime after 29 is the (2+9)th prime. [Silva]
The smallest prime which yields another when sandwiched between the sum of its digits: 1291. [Silva]