"Millions dollars" is incorrect.

In English, a plural noun used for counting or measuring purposes is always used with of, even if that noun just looks like a number:

• millions of dollars
• dozens of buckets
• thousands of lawyers

Note that this is a little different from simply using the number, like "two million dollars".

"Millions of dollars" is the correct form.

In English, a plural noun used for counting or measuring purposes is always used with of, even if that noun just looks like a number:

• millions of dollars
• dozens of buckets
• thousands of lawyers

Note that this is a little different from simply using the number, like "two million dollars".