18

Keg, \$ 1.92 * 10^{7813503} \$ bytes
Rather than put the actual program here, I put the program generator I used (written in Python 3):
prog = []
for char in reversed("Hello, World!"):
number = (ord(char)) * (ord('🂓') ** ord('🂓'))
add = ""
for l in str(len(str(number))):
...