More than 100 people were also wounded in the violence, in and around Baghdad, as well as in Salaheddin, Kirkuk, Diyala and Babil provinces, all afflicted by regular bloodshed.
The attacks came a day after a suicide bomber killed a key anti-Qaeda leader battling militants in the conflict-hit province of Anbar.
In today's deadliest incident, two vehicles rigged with explosives went off in the centre of Kirkuk, killing eight people and wounding nine, said the provincial health chief.
No group immediately claimed responsibility for the attack, but Sunni militants frequently detonate bombs in the disputed territory, capitalising on poor communication between Kurdish and central government security forces.
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Elsewhere in northern Iraq, a suicide truck bomb killed two people in Suleiman Bek, and two attacks in nearby Tuz Khurmatu, including a corpse booby-trapped with explosives, killed two others.
Both towns, like Kirkuk, lie in the disputed territory, which stretches from Iraq's border with Iran to its frontier with Syria.
In and around Baghdad, four people were killed by a car bomb in a commercial area of a Sunni-majority neighbourhood, while six others died in shootings and bombings inside the capital and on its outskirts.
Elsewhere, in the restive provinces of Diyala and Salaheddin, both north of Baghdad, attacks left three dead.
Today's violence came a day after a suicide bomber killed 11 people at a camp for families displaced from the conflict in the western desert province of Anbar, where security forces have struggled to retake territory from militants.