191999

Properties

Appears in sequences

• Primes that contain digits 1 and 9 only.at n=22A020457
• If k is a number with exactly two distinct decimal digits, say a and b, neither of which is 0 (i.e., a member of A101594), define the self-complement of k, SC(k), to be the number obtained by replacing a with b and vice versa. E.g. SC(232233) = 323322. Sequence contains primes p such that SC(p) is also a prime.at n=34A083983
• Sequence of primes p(n) such that 2*p(n)+3, 2*p(n+1)+3, 2*p(n+2)+3 are consecutive primes, where p(i) denotes the i-th prime.at n=19A088119
• Number of proper divisors of n!.at n=23A153823
• Primes of the form 3n^3-1.at n=9A200846
• Prime numbers consisting of only odd digits such that there is only one permutation of its digits that produces a prime number.at n=22A225421
• a(n) = 3*n^3 - 1.at n=40A345701
• Prime numbersat n=17326