No straightforward answer. But assuming you mean the US dollar:
In 2005, $15,700,000.00 from 1920 is worth:
$153,004,491.02 using the Consumer Price Index
$121,986,078.57 using the GDP deflator
$526,234,541.58 using the unskilled wage
$795,721,053.74 using the nominal GDP per capita
$2,212,422,898.52 using the relative share of GDP