R - Prime Numbers

This R code will generate tables containing the first 2 million numbers, whether that number is prime (divisible only itself and 1) or not, its lowest divisor (or 0 for primes).  The final two statements result in displaying the percent of non-prime numbers (92.55%) and prime numbers (7.45%).

num <- 1:2000000

prime <- rep("Prime", 2000000)

divisor <- rep(0, 2000000)

for (x in seq(from=2, to=2000000, by=1)) {

  z <- sqrt(x);

  for (y in 2:z) {

     if (x%%y == 0) {

       prime[x] <- "Non-Prime";

       divisor[x] <- y;

       break;

       }    

    }

}

ptable <- table(prime)

prop.table(ptable)