I have a really dull knife that I have never sharpened, can I simply strop to make it razor sharp?

Stropping is not a replacement for whetstone sharpening. When your knife edge became really dull, the micro teeth of the knife edge became blunt, and there are likely dents and chips as well. Stropping does not make those micro teeth regain their pointyness, and you certainly cannot strop away chips. Not only you won't improve the blade edge meaningfully, you'll also potentially damage your leather strop. When your knife is due for sharpening, it is essentially that you do a good job hand sharpen it on whetstones before using stropping. Stropping can be done between sharpening sessions, when the edge is still free of chips or dents, to regain a degree of sharpness by reducing the resistance from micro-teeth as a result of properly realigning them.