A well-known Islamic tradition holds that God has ninety-nine names that are known and recited, and a hundredth that is hidden, the Greatest Name, unknown to all but, in a widely told story, to the camel, which wears its knowing expression because it alone has learned it. The completeness of the hundred over against the ninety-nine expresses the idea that beyond every name that can be spoken there remains one that cannot. As the square of ten and the base of percentage, a hundred is also the natural figure for wholeness in ordinary speech, the hundred per cent, which is why it so readily stands for the complete and the perfect.
A hundred factors as 2^2 x 5^2 and carries 9 divisors in all. Summing its proper divisors gives 117, more than the number itself, which makes it an abundant number in the classical sense the Pythagoreans used to sort integers into deficient, perfect and abundant classes.
The genuine Pythagorean number philosophy that this modern chart borrows its name from left no writings of its own: Pythagoras and his early followers taught only by mouth, and what survives of their number theory comes instead through Nicomachus of Gerasa, whose Introduction to Arithmetic of the first century CE became the standard authority for a thousand years, and through Iamblichus, who drew on Nicomachus two centuries later; neither wrote anything resembling a name-and-birthdate numerology.