Can someone please explain the Riemann Hypothesis to me... in English? I've read so much about it but none of it makes a lot of sense. Also, what's so unsolvable about it?

Let $H_n$ be the nth harmonic number, i.e. $ H_n = 1 + \frac12 + \frac13 + \dots + \frac1n.$ Then, the Riemann hypothesis is true if and only if
$$ \sum_{d | n}{d} \le H_n + \exp(H_n)\log(H_n)$$
