整数部分为19。[详解]很明显,有:10/2000<1/1991+1/1992+1/1993+······+1/2000<10/1991,∴1991/10<1/(1/1991+1/1992+1/1993+······+1/2000)<2000/10,∴19.91<1/(1/1991+1/1992+1/1993+······+1/2000)<20,∴1/(1/1991+1/1992+1/1993+······+1/2000)的整数部分为19。
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