66563866624domain: NAppears in sequencesNumbers m such that sigma(m) is a perfect number.at n=13A146542Numbers n of the form 2^(A000043-1)*A046528 such that sigma(n) is a perfect number.at n=5A175906Numbers that can be expressed as the product of largest odd proper divisor and the sum of odd proper divisors.at n=20A225880