So the deepest part of Spongebob's ocean is 146,304.078638 kilometers, which is over 11x the diameter of our Earth which is 12,742 kilometers. The Mariana Trench is 10.984 kilometers deep, so the ratio between the Mariana Trench and Earth is 1,160.05x. Scaling Spongebob's Earth in a similar way, assuming Crush County is at a similar depth comparatively to the Mariana Trench, the planet would have a diameter of 169,720,190.227 kilometers, or 13,319.74x wider than our Earth. Scaling to the volume would give us a volume of 2.56 septillion cubic kilometers, or 2.56 trillion times larger than our own Earth. Multiplying this by the mass of the Earth, 5.972 septillion kilograms, gets us an Earth that weighs 15.29 undecillion kilograms.
However, that's not the only thing we can do with this, as we can also find out the GBE (Gravitational Binding Energy) to find the absolute minimum amount of energy needed to destroy this Earth. Plugging these values into
this GBE calculator gives us 110.27 sexdecillion joules needed to destroy this Earth. This is 1.1 GigaFoe (or over 1 billion supernovas), or very far into Solar System level.