http://billposer.org/Software/libuninum.html
Libuninum is a library that provides conversion in both directions between textual representations of numbers and integers. The library is written in C but provides a Tcl interface. Virtually all known number systems, living and dead, are covered:
Aegean Arabic_Alphabetic Arabic_Persian Arabic_Western Armenian Balinese Bengali Burmese Chinese_Counting_Rod_Early Chinese_Counting_Rod_Late Chinese_Counting_Rod_Early_No_Zero Chinese_Counting_Rod_Late_No_Zero Chinese_Legal_Simplified Chinese_Legal_Traditional Chinese_Regular_Simplified Chinese_Regular_Traditional Chinese_Regular_Place Common_Braille Cyrillic Devanagari Egyptian Ethiopic Ewellic_Decimal Ewellic_Hexadecimal French_Braille Glagolitic Greek_Lower Greek_Upper Gujarati Gurmukhi Hebrew_Early Hebrew_Late Hexadecimal_Lower Hexadecimal_Upper Japanese_Regular_Simplified Japanese_Regular_Traditional Japanese_Legal_Simplified Japanese_Legal_Traditional Japanese_Western_Mixed Kannada Kayah_Li Kharoshthi Khmer Klingon Lao Lepcha Limbu Malayalam Mandarin_Legal_Simplified Mandarin_Legal_Traditional Mandarin_Regular_Simplified Mandarin_Regular_Traditional Mongolian Mxedruli New_Tai_Lue Nko Ol_Chiki Old_Italic Old_Persian Oriya Osmanya Phoenician Roman_Lower Roman_Upper Russian_Braille Saurashtra Shan Sinhala Sundanese Suzhou Tamil_Place Tamil_Traditional Telugu Tengwar_Decimal Tengwar_Duodecimal Thai Tibetan Vai Verdurian Western_Lower Western_Upper Xucuri_Lower Xucuri_Upper