21488 has 20 divisors (see below), whose sum is σ = 44640. Its totient is φ = 9984.

The previous prime is 21487. The next prime is 21491. The reversal of 21488 is 88412.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21481) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 233 + ... + 311.

It is an arithmetic number, because the mean of its divisors is an integer number (2232).

2²¹⁴⁸⁸ 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 21488, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22320).

21488 is an abundant number, since it is smaller than the sum of its proper divisors (23152).

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

21488 is a wasteful number, since it uses less digits than its factorization.

21488 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104 (or 98 counting only the distinct ones).

The product of its digits is 512, while the sum is 23.

The square root of 21488 is about 146.5878576145. The cubic root of 21488 is about 27.8013145696.

The spelling of 21488 in words is "twenty-one thousand, four hundred eighty-eight".