九次方數(英語:Ninth power number)係喺算術代數入面,寫得成嘅數,其中一定係整數,即: n9 = n × n × n × n × n × n × n × n × n.

九次方數嘅序列為:

0, 1, 512, 19683, 262144, 1953125, 10077696, 40353607, 134217728, 387420489, 1000000000, 2357947691, 5159780352, 10604499373, 20661046784, 38443359375, 68719476736, 118587876497, 198359290368, 322687697779, 512000000000, 794280046581, 1207269217792,... (OEIS數列A001017