AD 2015 was in the 21st century
It is the 21st century
The 21st Century AD.
The 21st century AD.
Both. It was the last year of the 21st century BC, and the first year of the 21st century AD.
2004 is in the twenty-first century.
The 21st century started on January 1, 2001 and will continue until December 31, 2100. The 21st century is the first century of the 3rd millennium.
18th century So 2012 is 21st century, etc.
1866 was in the 19th century. 1966 was in the 20th century. 2066 will be in the 21st century.
2001- 3000
the first century. AD is after death, and anything up to 99 AD is the first century. then comes the second, third, fourth, etc. (technically we live in the 21st century AD).
The 21st century. ACE means After the Common Era. Just another way of saying AD.