21264 has 20 divisors (see below), whose sum is σ = 55056.
Its totient is φ = 7072.
The previous prime is 21247. The next prime is 21269. The reversal of 21264 is 46212.
Adding to 21264 its reverse (46212), we get a palindrome (67476).
It can be divided in two parts, 212 and 64, that added together give a triangular number (276 = T23).
It is a nude number because it is divisible by every one of its digits.
It is a nialpdrome in base 16.
It is not an unprimeable number, because it can be changed into a prime (21269) by changing a digit.
21264 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
It is a pernicious number, because its binary representation contains a prime number (5) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 174 + ... + 269.
221264 is an apocalyptic number.
21264 is a gapful number since it is divisible by the number (24) formed by its first and last digit.
It is an amenable number.
21264 is an abundant number, since it is smaller than the sum of its proper divisors (33792).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27528).
21264 is a wasteful number, since it uses less digits than its factorization.
21264 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 454 (or 448 counting only the distinct ones).
The product of its digits is 96, while the sum is 15.
The square root of 21264 is about 145.8218090685.
The cubic root of 21264 is about 27.7043727104.
The spelling of 21264 in words is "twenty-one thousand, two hundred sixty-four".