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[that is, $2^{30}\left({2^{31} - 1}\right)$], 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.

Also see

 * Theorem of Even Perfect Numbers