二十多

èrshíduō

over 20

二十面体

èrshímiàntǐ

icosahedron

二十世纪

èrshíshìjì

20th century

二十六岁

èrshíliùsuì

26 years old

二十四史

ÈrshísìShǐ

the Twenty-Four Histories (25 or 26 in modern editions), collection of books on Chinese dynastic history from 3000 BC till 17th century

二十四孝

ÈrshísìXiào

the Twenty-four Filial Exemplars, classic Confucian text on filial piety from Yuan dynasty

二十一条

ÈrshíyīTiáo

the Japanese Twenty-One Demands of 1915

二十一点

èrshíyīdiǎn

blackjack (card game)

二十五史

èrshíwǔshǐ

twenty four dynastic histories (or 25 or 26 in modern editions)

二十八宿

èrshíbāxiù

the twenty-eight constellations

二十一世纪

èrshíyīshìjì

21st century

三七二十一

sānqīèrshíyī

three sevens are twenty-one (idiom)

二十四节气

èrshísìjiéqi

the 24 solar terms, calculated from the position of the sun on the ecliptic, that divide the year into 24 equal periods

茄二十八星瓢虫

qiéèrshíbāxīngpiáochóng

28-spotted ladybird

不管三七二十一

bùguǎnsānqīèrshíyī

regardless of the consequences

二十年目睹之怪现状

ÈrshíNiánMùdǔzhīGuàiXiànzhuàng

The Strange State of the World Witnessed Over 20 Years, novel by late Qing novelist Wu Jianren [[吳趼人]], classified as "novel of denunciation" [[譴責小說|谴责小说<qiǎnzéxiǎoshuō>]]

一部二十四史，不知从何说起

yībùèrshísìshǐ,bùzhīcónghéshuōqǐ

It's a long and intricate story, I hardly know where to start.