0x10000000 is a hexadecimal? why is it so long? what value is it in ASCII format?

I'm a junior JAVA developer and I'm supposed to develop some transaction messages. The given specifications include hex value 0x10000000 or 0x20000000, and I'm really bad at data communications, I refer mostly to http://www.asciitable.com/ to help me translate between formats, but I'm really confused about this 0x10000000. In decimal format, it is 268,435,456, unusually big, and I couldn't find anything on ASCII format.

I'm just wondering why they would provide that hex value cause I'm missing something here, and the previous version of this transaction device I'm working on has hex value in 4 characters like 0x33 or 0x31. What are the differences here or what am I missing out here (in terms of understanding)?