Barlow's Prediction

Prediction

 * " ascertained that $2^{31} - 1 = 2147483647$ is a prime number; and this is the greatest at present known to be such, and, consequently, the last of the above perfect numbers, which depends upon this, is the greatest perfect number known at present, and probably the greatest that ever will be discovered; for, as they are merely curious without being useful, it is not likely that any person will attempt to find one beyond it."

This statement was made by, in his 1811 work.

He repeated this statement word for word in his 1814 work.

See the definition of Mersenne prime to follow up on exactly how inaccurate that prediction was.