Which compound (समास) type is present in the word 'सप्तर्षि'?

The word 'सप्तर्षि' splits up into 'सप्त ऋषियों का समूह' (A group of seven sages). Whenever the first term of a compound is a numeral (संख्यावाचक विशेषण) and the entire word stands for a collective group, it is categorized as Dvigu Samas.