Is there any range specification for autonomous systems?

ASNs are drawn from a16-bit number field, allowing for65,536 possible values.The block of ASNs from64,512 through65,534 is designated for private use. ASN23,456 is reserved for use in ASN pool transition. The remainder of the values, from1 through to64,511 (less23,456), are available for use in Internet routing.

16-bit integers, Range0 and65535,IANA has reserved AS64512 through to AS65535 to be used as private ASNs.

you can check this for answer to your question:

https://www.arin.net/resources/request/asn.html

offcourse range for minumum and maximum are always there you can type ? after each prtotocol and see the range. for EIGRP the As number should be same to form a neighbor relation ship. OSPf depends on Area and BGP its defferent you can define with each neighbor also their remote-as