Problem with prime number code

// Calculating Prime Numbers

int number;

void setup()
{
  Serial.begin(9600);
}

void loop()
{
 for(number = 1; number < 1000; number++)
  {
    if(number / number = 1 || number / 1 = number ) // ERROR - VALUE REQUIRED AS LEFT OPERAND OF ASSIGNMENT...what?
    {
      serial.println(number);
    }
    else
    {
      delay(500);
    }
  }
}