R Program to Check Prime Number

# Program to check if the input number is prime or not

# take input from the user
num = as.integer(readline(prompt="Enter a number: "))

flag = 0
# prime numbers are greater than 1
if(num > 1) {
    # check for factors
    flag = 1
    for(i in 2:(num-1)) {
        if ((num %% i) == 0) {
            flag = 0
            break
        }
    }
} 

if(num == 2)    flag = 1
if(flag == 1) {
    print(paste(num,"is a prime number"))
} else {
    print(paste(num,"is not a prime number"))
}

Output 1

Enter a number: 25
[1] "25 is not a prime number"

Output 2

Enter a number: 19
[1] "19 is a prime number"