The special number field sieve can factorize numbers with more than one large factor.
From the en.wikipedia.org
They successfully managed to factorize 21.
From the en.wikipedia.org
Who did factorize it, then?
From the guardian.co.uk
Algorithms that recursively factorize the DFT into smaller operations other than DFTs include the Bruun and QFT algorithms.
From the en.wikipedia.org
These can be found experimentally using lattice reduction, and are useful in setting up the special number field sieve to factorize a Fibonacci number.
From the en.wikipedia.org
So if the visible universe were the extent of physical reality, physical reality would not even remotely contain the resources required to factorize such a large number.
From the guardian.co.uk
If a number has only one very large factor then other algorithms can factorize larger numbers by first finding small factors and then making a primality test on the cofactor.
From the en.wikipedia.org
More examples
Resolve (a polynomial) into factors
(factorization) (mathematics) the resolution of an entity into factors such that when multiplied together they give the original entity
To create a list of factors; To divide an expression into a listing items that, when multiplied together, will produce the original quantity