The number of electors each state has is equal to the number of representatives it has in Congress — both the Senate and the House of Representatives combined. The least possible number of electors from any given state is three, one for each of the two senators and one for a single representative.
The total number of electors in the Electoral College is 538. The state with the largest number of electors is California with 55. California has two senators and 53 representatives in the House. The 26th Amendment also grants three electors to Washington, D.C. Additional, states with only three electors are Alaska, Delaware, Montana, North Dakota, South Dakota, Vermont and Wyoming.