Final answer:
The number 0.723549 is not a natural number, a whole number, or an integer but is a rational number. It can be expressed as a fraction, so it is not an irrational number.
Step-by-step explanation:
The number 0.723549 is not a member of the natural numbers, whole numbers, or integers because all these sets include only numbers without fractional or decimal parts. Meanwhile, since it can be expressed as a fraction (by placing it over a denominator appropriately scaled by a power of 10), it is a member of the rational numbers. It is not an irrational number because irrational numbers cannot be expressed as a fraction of two integers.