Don’t capitalize sun. (Its proper name is Sol, from which we get solar system — all others are technically stellar systems — and sun is the common noun.)
You can keep the numerals if you want — this example may count as science writing — or you can change the first one to one hundred seventy-four trillion. (Don’t write it as one hundred and seventy-four, because that means 100.74, and don’t hyphenate trillion into the rest.)
Add a comma after mass.
Change the ampersand (that’s the & thing) to and.
Delete the comma after hence.
You can change 1.5 cm to one and a half (or one-point-five) centimeters (or centimetres — the writer of this example obviously prefers UK English spellings, and centimetre goes with tonne instead of ton) if you like.
The sun lost one hundred seventy-four trillion tonnes of mass, and hence the Earth’s orbit increased by one-point-five centimetres.