The official Australian government page https://www.nationalsecurity.gov.au/national-threat-level/current-national-terrorism-threat-level features the following quote.
This is because there are a small number of people in Australia and overseas who want to cause Australia harm.
If instead of “a small number of” the page used an adjective like “few” I would see the sentence as correct. It strikes me as odd, though, how with the sentence as it is,”are” is used instead of “is” as I see “number” as the subject of the sentence.
Is the sentence correct in its current form? If so, what special construct is “a small number of” and why can it be used as an adjective instead of being the subject of the sentence?