That is the correct spelling of "half million" (500,000). The terminology for the determiner (adjective) would properly be "a half million" or "one-half million" or more colloquially "half a million."
e.g.
There were a half million refugees from the flood.
More than one-half million residents were without power.
As many as half a million cars were affected by the recall.
500,000
Half a million Five hundred thousand
It is three and a half million US dollars.
Six million five hundred-thousand - or - six and a half million.
To write four and a half million in numbers, you would write 4,500,000. This is because the "and a half" part represents 500,000, which is half of a million. Therefore, when combined with the four million, it becomes 4,500,000.
two and a half million
Half a million is 500,000
As a number it is: 500,000 = half a million
can you saw me how can you write one and a half million in digits
Eighty million.
4,500,000
1,500,000