The number, 197, is called a circular prime because all rotations of the digits: 197, 971, and 719, are themselves prime.
There are thirteen such primes below 100: 2, 3, 5, 7, 11, 13, 17, 31, 37, 71, 73, 79, and 97.
How many circular primes are there below one million?
import math def isPrime(n): for i in range(2,int(math.sqrt(n))+1): if n%i==0: return False return True def isCyclePrime(n): num = list() while n > 0: num.insert(0,n%10) n /= 10 for i in range(len(num)): s = '' for k in range(i,len(num)): s += str(num[k]) for j in range(i): s+=str(num[j]) if isPrime(int(s)) == False: return False return True def main(): count =0 for i in range(2,1000000): if isCyclePrime(i): count += 1 print count if __name__ == "__main__": main()