51119

Appears in sequences

• Composite numbers n such that the sum of divisors of n, sigma(n), divided by the number of divisors, d(n) and sigma(n) minus n are both rational squares.at n=11A049226
• Reverse of smallest prime factor of k = largest prime factor of k+1; a(1)=1.at n=38A071392
• Numbers k such that 2^(k+1) == 1 (mod k).at n=33A187787