Sexdecillion is an extremely large number used in mathematics and science, but there are other synonyms available that can make it easier to understand the size of the number. Some alternatives for sexdecillion include quindecillion, quattuordecillion, tredecillion, and duodecillion. These words represent numbers with 15, 14, 13, and 12 zeros respectively. Other synonyms for sexdecillion that can be used interchangeably include one nonillion, one octillion, and one trillion trillion. These synonyms can come in handy when dealing with complex mathematical problems or science calculations that require the use of very large numbers.