Google Page rank work on Website content How many inbound link and outbound link Website Traffic Website Popularity Website Back links SEO friendly Content Submission Details This all factor google include in PR update time. and you want to check your website page rank so download google tool bar you can easily check your page rank daily and other one google update PR each and every 3 or 4month before 5 or 6day backlink update is gone so check your website back link
Google has it's own Page Rank Calculations and you should have been focused on quality links rather then quantity of links it's should be your related sites back links, and the number of out bound links is lower then 25 it's has algorithm like PR(A) = (1-d) + d (PR(T1)/C(T1) + ... + PR(Tn)/C(Tn)) where PR(A) is the PageRank of page A, PR(Ti) is the PageRank of pages Ti which link to page A, C(Ti) is the number of outbound links on page Ti and d is a damping factor which can be set between 0 and 1.