It is a foreign "Wertbrief" that is an insured letter to London dated 26.9.23.from the OPD Hamburg. The value is declared in figures and words, "84 Million Marks". The value is also recorded in the International Gold Francs currency "2 2/13 Francs". Weight is recorded as being "44g" So the rate was calculated as follows:

Foreign letter (20g) 750 Thousand
Each extra 20g 375 Thousand(2ndweight)
44g so another 375 Thousand(3rdweight)
registration fee 250 Thousand
Insurance Fee 750 Thousand
Total 2,500,000 Million

Reverse also has wax seals of the Hamburg postal inspectors and arrival cancel of London. Wertbrief foreign letters from the hyper-inflation period are scarce and with a multiple franking such as this it is in all probability a unique piece of postal history