Just to clarify, what you see on the Elections website -- SMCs and GRCs -- are the two types of electoral divisions in Singapore. The numbers on that page refer to them, not polling stations. For example, the electoral division Bukit Batok SMC has 25,727 electors. GRCs are larger divisions that may have over 100,000 electors.
As a further update, the Elections Department has just uploaded data on Number of Spoilt Votes and Number of Invalid Votes in machine-readable format. This means all the required data is now available to the public in machine-readable format. Previously, data on Number of Spoilt Votes and Number of Invalid Votes was available only as PDF.
The URLs are the same as before: