Divisor Count of 6561

Example of Use of $\tau$ Function

 * $\map \tau {6561} = 9$

where $\tau$ denotes the $\tau$ Function.

Proof
From Tau Function from Prime Decomposition:
 * $\displaystyle \map \tau n = \prod_{j \mathop = 1}^r \paren {k_j + 1}$

where:
 * $r$ denotes the number of distinct prime factors in the prime decomposition of $n$
 * $k_j$ denotes the multiplicity of the $j$th prime in the prime decomposition of $n$.

We have that:
 * $6561 = 3^8$

Thus:

The divisors of $6561$ can be enumerated as:
 * $1, 3, 9, 27, 81, 243, 729, 2187, 6561$