21248 has 18 divisors (see below), whose sum is σ = 42924. Its totient is φ = 10496.

The previous prime is 21247. The next prime is 21269. The reversal of 21248 is 84212.

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (21247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 215 + ... + 297.

2²¹²⁴⁸ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21248, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21462).

21248 is an abundant number, since it is smaller than the sum of its proper divisors (21676).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21248 is an frugal number, since it uses more digits than its factorization.

21248 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99 (or 85 counting only the distinct ones).

The product of its digits is 128, while the sum is 17.

The square root of 21248 is about 145.7669372663. The cubic root of 21248 is about 27.6974222905.

The spelling of 21248 in words is "twenty-one thousand, two hundred forty-eight".