Football Leaks published De Gea's contract with Real Madrid before the deal turned into a fiasco at the deadline. Here's The Guardian's report about it.
It shows the Spain international would have received a figure of €11,818,182 (£9.2m) for each season from 2015-16 to 2020-21.
There is also mention of a break clause of €500m (£388m), which De Gea would have been obliged to pay if he walked out on his contract.
[De Gea's new Manchester United] deal was reportedly worth £200,000 per week. The figures from the Football Leaks document equate to around £176,000 per week.
It seems that De Gea is still on Real Madrid's shortlist to improve the team next summer, although Manchester United will most likely be reluctant to sell the goalkeeper once again, meaning that Florentino Pérez will need to make a big offer.
De Gea is playing fairly well for Manchester United this season, just like Keylor Navas in Real Madrid.