Looking up, Zoro's bounty has a lot of references. The 1111 part references his birthday and the Shimotsuki. "Zorome", which is to line up several numbers together, can infer to good fortune in something like gambling. Zoro's been noted to be quite lucky. And finally, Oda loves to incorporate goroawase on the bounties. 110 part of his bounty spells out hyakuju (百十) which is identical sounding to hyakuju for Beasts (百獣). Zoro's been likened to a wild beast at times.