Shorten emoji strings with hexadecimal / base64 ? (Suggestion)

Hi- I'm building a bot that creates pictures using many emojis at once. I noticed that emojis fill up the character count pretty quickly. But this is mostly because emojis are very long numerical strings. 
<a:someemoji:123805812588424>

Could the length be reduced by also supporting a different base than 10?
Like so:
Hex: <h:someemoji:7099C97AFF88>
Base64: <b:someemoji:776I>
etc

I'm sure there are technical limits I don't know about - but it could be helpful for reducing the data being sent with each emoji-filled message.