• 22 can be written using four 4's:
• Deleting all the even digits from 222 = 4194304 we obtain a prime (193).
22 is nontrivially palindromic in base 10.
22 is an esthetic number in base 6, because in such base its adjacent digits differ by 1.
It is a semiprime because it is the product of two primes.
It is a nude number because it is divisible by every one of its digits.
22 is an idoneal number.
It is the 11-th Perrin number.
22 is a nontrivial repdigit in base 10.
It is a plaindrome in base 4, base 6, base 8, base 9, base 10, base 12, base 13, base 14, base 15 and base 16.
It is a nialpdrome in base 3, base 5, base 7, base 10 and base 11.
It is a zygodrome in base 10.
It is a congruent number.
It is a self-describing number.
22 is the 4-th pentagonal number.
22 is the 3-rd centered heptagonal number.
22 is a wasteful number, since it uses less digits than its factorization.
22 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 13.
The square root of 22 is about 4.6904157598. The cubic root of 22 is about 2.8020393307.