"Priority number" refers to a numerical value assigned to something that determines its level of importance or the order in which it should be done. Full definition
Then sleep becomes priority number one on our to - do list, and for good reason. (parsleyhealth.com)
So, going forward, is PC still priority number one for you? (vg247.com)
In my previously mentioned experiment, I measured the effect that making my marriage priority number one had on different areas of my life. (relevantmagazine.com)