Unit prefix for 10-1 is deci, for 10-2 centi, for 10-3 milli, for 10-6 micro and so on. Powers greater or equal one also have names: 101 is deca, 102 is hecto, 103 is kilo etc..
We can say, for example, “Multiply the measurement in millimeters by 1000 and you have it in micrometers.”
But is there a prefix (even if it's just exotic) to express the zeroth power as an alternative to just using no prefix, like in “Divide the measurement in millimeters by 1000 and you get it in meters.”?
For example if we want to say it in a general way, it becomes pretty cumbersome: “Divide the measurement in milli by 1000 and you get the prefix-less unit itself.”