English word vigintillion comes from English million ((long and short scales) The cardinal number 1,000,000: 106.), English viginti- (Twenty.)

Detailed word origin of vigintillion

Dictionary entry	Language	Definition
million	English (eng)	(long and short scales) The cardinal number 1,000,000: 106.
viginti-	English (eng)	Twenty.
vigintillion	English (eng)	(cardinal) Originally, the twentieth power of a million, 10120; now (originally US) more usually 1063.