Humans invented numbering systems but can only discover numbers, not invent new ones. Unlike the sensation of colors, a discovered number like pi or 666 is the same number in all dimensions of space, time, and beyond.
Yes, they are. The numbers we HAPPEN to use today are of Hindu/Arabic development, or as the site says: Arabic numerals or Hindu-Arabic numerals or Indo-Arabic numerals.
http://en.wikipedia.org/wiki/Arabic_numerals
The ZERO is the real amazement...the concept of "not any" and putting it with 1-9 and then making our counting go on almost forever.