969 years. Although by our standards the pre-flood people lived long lives, one of the purposes of this genealogy was to be a polemic against Mesopotamian mythology, in which people lived for tens of thousands of years. Babylonian texts record the lives of ten kings who were demigods and lived exceptionally long lives in pre-flood times. The Sumerian King List names eight kings prior to the flood who lived a total of 241,000 years. The OT criticizes such myths; humans lived long lives before the flood, but they were not demigods who lived for an exaggerated amount of time.ESV Archaeology Study Bible, p. 21
I find this to be an interesting note on the purpose of the pre-flood genealogy in Genesis. Who knew that a pre-flood life of 969 years at that time of Moses’ writing might come across as awfully conservative? If you want to peruse the Sumerian King List, you can do so here.