Fast method to fin prime factor

findDivisor <- function(num){
  p = vector('numeric', 1e5)
  k = 1
  step_p = 1e7
  repeat{
    s = min(k, num):min(num, k+step_p)
    tmp = which(num %% s == 0)
    if (length(tmp) > 0)
    {
      if (sum(p!=0)+length(tmp) > 1e5)
        p = c(p, rep(0, 1e5))
      p[(sum(p!=0)+1):(sum(p!=0)+length(tmp))] = s[tmp]
    }
    if (k > num)
      break
    k = k + step_p
  }
  unique(p[p!=0])
}

primefactorFast <- function(num){
  p <- findDivisor(num)
  isPrime <- function(num){
    return(length(findDivisor(num)) == 2)
  }
  p <- p[sapply(p, isPrime)]
  e <- vector('numeric', length(p))
  e_basic <- 1
  step_e <- 5
  subset_e <- 1:length(p)
  repeat{
    m = num %% sweep(matrix(replicate(step_e, p[subset_e]), length(p[subset_e])), 2,
      e_basic:(e_basic + step_e - 1), '^') == 0
    e[subset_e] = e[subset_e] + rowSums(m)
    e_basic = e_basic + step_e
    subset_e = which(apply(m,1,all))
    if (is.null(subset_e) || (length(subset_e) == 0))
      break
  }
  return(list('pfactor'=p, 'multi'=e))
}
testNum = 2^11*3^6*47
log10(testNum) # [1]  7.846155
st = proc.time()
out = primefactorFast(testNum)
proc.time() - st
#   user  system elapsed
#   5.74    0.78    6.52