Kenan lived after he fathered Mahalalel 840 years and had other sons and daughters.
We have here all that the Holy Ghost thought fit to leave upon record concerning five of the patriarchs before the flood, Seth, Enos, Cainan, Mahalaleel, and Jared. There is nothing observable concerning any of these particularly, though we have reason to think they were men of eminence, both for prudence and piety, in their day: but in general, I. Observe how largely and expressly their generations are recorded.
Commenting on Genesis 5:6-20
And all the days of Mahalaleel were eight hundred ninety and five years, and he died. He also is spoken well of by the Arabic writers (p) as a good governor, a pious man that walked in the way of righteousness; and when he died blessed his children, and adjured them by the blood of Abel, not to suffer any of theirs to descend from...
Gen 5:3-32 As Adam was created in the image of God, so did he beget “in his own likeness, after his image;” that is to say, he transmitted the image of God in which he was created, not in the purity in which it came direct from God, but in the form given to it by his own self-determination, modified and corrupted by sin.
Commenting on Genesis 5:3-32