21552 has 20 divisors (see below), whose sum is σ = 55800. Its totient is φ = 7168.

The previous prime is 21529. The next prime is 21557. The reversal of 21552 is 25512.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (21557) by changing a digit.

21552 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, 177 + ... + 272.

It is an arithmetic number, because the mean of its divisors is an integer number (2790).

2²¹⁵⁵² is an apocalyptic number.

It is an amenable number.

21552 is an abundant number, since it is smaller than the sum of its proper divisors (34248).

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 (27900).

21552 is a wasteful number, since it uses less digits than its factorization.

21552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 460 (or 454 counting only the distinct ones).

The product of its digits is 100, while the sum is 15.

The square root of 21552 is about 146.8059944280. The cubic root of 21552 is about 27.8288884181.

The spelling of 21552 in words is "twenty-one thousand, five hundred fifty-two".