211000: two hundred and eleven thousand
3503456: three million, five hundred and three thousand, four hundred and fifty six
1234567890: one billion, two hundred and thirty four million, five hundred and sixty seven thousand, eight hundred and ninty
总之,英语的数字通常是三位一级,例如1234567890通常就被写作1,234,567,890. 现在常用的也就是十亿以内,可能在写英文说法时不用加逗号,但是读起来就得像是我写的那样.
常用单位：
billion 十亿
million 百万
thousand 千
如果一个数比的单位比千亿还要多的话,我就实在是不知道怎么说了,这点我需要道歉.
希望我的回答能给你带来帮助!