All four of Landau's "unattackable" problems concerned these entities.
All four of Landau's "unattackable" problems concerned these entities. One of those problems, Legendre's conjecture, claims that for all positive integers n, one of them is found between n squared and quantity n plus one squared; another states that any even integer greater than two can be written as a sum of two of them and is known as the (*) Goldbach conjecture. Many encryption methods rely on multiplying two of them, and they can be found using the sieve of Eratosthenes. For 10 points, name these numbers whose only factors are one and themselves.
All four of Landau's "unattackable" problems concerned these entities.
{prime} numbers [or {primes}]