21588 has 24 divisors (see below), whose sum is σ = 57792. Its totient is φ = 6144.

The previous prime is 21587. The next prime is 21589. The reversal of 21588 is 88512.

21588 is an esthetic number in base 13 and base 16, because in such bases its adjacent digits differ by 1.

It is an interprime number because it is at equal distance from previous prime (21587) and next prime (21589).

21588 is an undulating number in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21587) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45 + ... + 212.

It is an arithmetic number, because the mean of its divisors is an integer number (2408).

2²¹⁵⁸⁸ is an apocalyptic number.

21588 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21588 is an abundant number, since it is smaller than the sum of its proper divisors (36204).

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 (28896).

21588 is a wasteful number, since it uses less digits than its factorization.

21588 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271 (or 269 counting only the distinct ones).

The product of its digits is 640, while the sum is 24.

The square root of 21588 is about 146.9285540663. The cubic root of 21588 is about 27.8443747254.

Adding to 21588 its sum of digits (24), we get a palindrome (21612).

It can be divided in two parts, 215 and 88, that added together give a palindrome (303).

The spelling of 21588 in words is "twenty-one thousand, five hundred eighty-eight".