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8561

8561 is an integer in the natural numbers, falling between 8560 and 8562. In mathematics, it is notable for being an odd composite number.

Its prime factorization is 7 × 1223, with both factors prime. Therefore, 8561 is a semiprime, a

Some basic modular observations about 8561 include that it is congruent to 0 modulo 7 and congruent

In practical terms, 8561 is primarily of interest in number theory as a concrete example of a

type
of
composite
number
formed
by
the
product
of
exactly
two
primes
counting
multiplicity.
Because
of
its
factors,
8561
is
divisible
by
7,
but
not
by
2,
3,
or
5.
The
number
1223
is
also
prime,
confirming
the
uniqueness
of
its
prime
factorization
under
the
fundamental
theorem
of
arithmetic.
to
1
modulo
8,
since
8561
≡
0
(mod
7)
and
8561
≡
1
(mod
8).
Its
digit
sum
is
20,
so
it
is
not
divisible
by
3.
semiprime.
Due
to
its
small
size,
it
is
not
used
in
modern
cryptography,
but
it
serves
as
a
simple
case
study
for
factoring
and
the
properties
of
products
of
two
primes.