420421

Properties

Appears in sequences

• Primes formed by concatenating k with k+1, where k+1 is a prime.at n=20A134428
• Numbers k such that psi(phi(k))/k > psi(phi(m))/m for all m < k, where phi is Euler's totient function (A000010) and psi is the Dedekind psi function (A001615).at n=31A293712
• Prime numbersat n=35424