89 is a prime number.
89 is the smallest prime whose digits, 8 and 9, are composites.
89 is the eleventh Fibonacci number.
89 is the only two-digit number that is the sum of its first digit and its second digit squared: 8 + 92 = 89.
A sunflower head often displays florets in spirals of 55 and 89 around the outside.
Source: Number Gossip