# Are All Perfect Numbers Even?/Progress/Prime Factors/Historical Note

## Historical Note on Prime Factors of Odd Perfect Number

Bryant Tuckerman published a proof in $1973$ that an odd perfect number $P$ has the properties that:

either:
at least one of the prime powers factoring $P$ is greater than $10^{18}$
the power of such a prime factor is even
or:
there is no divisor of $P$ less than $7$.

Peter Hagis, Jr. published a proof in $1980$ that an odd perfect number has at least $8$ distinct prime factors.

Peter Hagis, Jr. and Graeme L. Cohen published a proof in $1998$ that an odd perfect number has at least one prime factor which is greater than $1 \, 000 \, 000$.

Pascal Ochem and Michaël Rao published a proof in $1998$ that:

at least one of the prime powers factoring an odd perfect number is greater than $10^{62}$
an odd perfect number has more than $101$ prime factor (not neessarily distinct).