Is there a word for a number with commas?

Solution 1:

The following sentence is a professional request:

Please use delimiters with large numbers.

A delimiter is a sequence of one or more characters used to specify the boundary between separate, independent regions in plain text or other data streams.

Delimiters are particularly helpful in mathematical notation:

For ease of reading, numbers with many digits may be divided into groups using a delimiter.

Source: en.wikipedia.org Emphasis mine

Solution 2:

Commonly "thousands separator" is the name of the comma in this format; that doesn't translate nicely to an adjective, so perhaps you could rephrase your statement slightly to tell them to use "numbers with thousands separators" (rather than the clumsy "thousands separated numbers").