3. In a row, all natural numbers less than a billion that have exactly 13 natural divisors (including one and the number itself) were written down. How many of them have an even sum of digits?
6.I.3. If $n=p_{1}^{s_{1}} p_{2}^{s_{2}} \ldots p_{k}^{s_{k}}$, then the number of divisors of the number $n$ is $\left(s_{1}+1\right)\left(s_{2}+1\right) \ldots\left(s_{k}+1\right)$. Since the number of divisors of the given number is a prime number, the number itself is a power of a prime number; in this case $n=p^{12}$. From the following table, it is clear that the required numbers are $3^{12}$ and $5^{12}$.

| $p$ | 2 | 3 | 5 | 7 |
| :---: | :---: | :---: | :---: | :---: |
| $p^{12}$ | 4096 | 531441 | 244140625 | 13841287201 |

Answer: two numbers.