He is considered to be the pre-eminent mathematician of the 18th century, and one of the greatest mathematicians ever to have lived. He is also one of the most prolific mathematicians ever; his collected works fill 60–80 quarto volumes. -- https://en.wikipedia.org/wiki/Leonhard_Euler
Who is the most prolific mathematician? Either Leonhard Euler, if counting by single authorship, or Paul Erdös, if counting by collaborative publications. -- http://wiki.answers.com/Q/Who_is_the_most_prolific_mathemati...
The most prolific mathematician of all time, publishing close to 900 books. -- http://www.guardian.co.uk/culture/2010/apr/11/the-10-best-ma...
Euler's work in mathematics is so vast that an article of this nature cannot but give a very superficial account of it. He was the most prolific writer of mathematics of all time. -- http://www-gap.dcs.st-and.ac.uk/~history/Biographies/Euler.h...
He is considered to be the pre-eminent mathematician of the 18th century, and one of the greatest mathematicians ever to have lived. He is also one of the most prolific mathematicians ever; his collected works fill 60–80 quarto volumes. -- https://en.wikipedia.org/wiki/Leonhard_Euler