It's the suspension bridge with the longest central span, at 1.25 miles (2.86 miles long in total).
The world's longest bridge which is a suspension bridge remains the Mackinac Bridge, at just shy of 5 miles long in total (central span of less than 3/4 mile).
Kinda. The Mackinac Bridge is the longest bridge in the world which contains a suspension component, but the majority of the bridge is not actually a suspension bridge. Only 1/3 of the Mackinac bridge is suspension (2,625m of 8,038m total length).
The longest (entirely) suspension bridge in the world is the Kurushima Kaikyō Bridge in Japan, with a suspension length of 4,015m. But it in turn is comprised of four towers, so it is effectively two suspension bridges strung together, which is why usually length of the central span is the benchmark for "longest suspension bridge in the world" and therefore why the 1915 Çanakkale Bridge is claiming the title.
> The longest (entirely) suspension bridge in the world is the Kurushima Kaikyō Bridge in Japan, with a suspension length of 4,015m
4,015m is 2.5 miles. The parent comment to you said that the 1915 Çanakkale bridge is 2.86 miles long in total. If those numbers are correct, the 1915 Çanakkale bridge would appear to be the longest suspension bridge by all measures, not just central span. I don't think it has anything to do with number of towers.
The 1915 Çanakkale Bridge is not an entirely suspension bridge either. The suspension part is in total 3,563m long, with the approach viaducts adding an additional 1,045m, for a total length of 4,608m (2.86mi).
This image[1] can help give you an idea of the additional length that is added by the approach without actually being part of the suspension bridge.
Central span length is definitely more interesting than overall length. Technically not a single bridge, but the Chesapeake Bay Bridge-Tunnel is over 17 miles long.
The world's longest bridge which is a suspension bridge remains the Mackinac Bridge, at just shy of 5 miles long in total (central span of less than 3/4 mile).