I often see numbers written like this: 19.456 thousand or this: 19,456 thousand. Neither is correct in English, and both may cause confusion.
我经常看到有人这么用英语来写数字：19.456千，或者19,456千。这两种写法都不对，而且会引起误会。
In English we do not mix numerals and words unless we are using the words “million”, “billion”, “trillion” etc. So, it is wrong to write, e.g., 24 thousand; instead you should write 24,000 or twenty-four thousand. 考试用书
在英语中，除了表示“百万”，“十亿”，“万亿”等词外，数字和单词是不能混用的。比如，你如果写24千，那就是错的，你应该写成24,000 或者twenty-four thousand（用数字，就全部用数字；用单词，就全部用单词；不能夹杂着用）。
19.456 thousand or 19,456 thousand should therefore be written in English in either of the following ways:
所以，19.456千，或者19,456千应该按照下面这样的方式写才对：
19,456,000 or 19.456 million (read as “nineteen million, four hundred and fifty-six thousand” or “nineteen point four-five-six million”)
19,456,000 或者19.456 million（读作，一千九百四十五万六千）。
