21531360 has 96 divisors (see below), whose sum is σ = 70060032. Its totient is φ = 5552640.

The previous prime is 21531343. The next prime is 21531361. The reversal of 21531360 is 6313512.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531361) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14157 + ... + 15603.

It is an arithmetic number, because the mean of its divisors is an integer number (729792).

Almost surely, 2^21531360 is an apocalyptic number.

21531360 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21531360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35030016).

21531360 is an abundant number, since it is smaller than the sum of its proper divisors (48528672).

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

21531360 is a wasteful number, since it uses less digits than its factorization.

21531360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1496 (or 1488 counting only the distinct ones).

The product of its (nonzero) digits is 540, while the sum is 21.

The square root of 21531360 is about 4640.1896512966. The cubic root of 21531360 is about 278.2000182268.

Adding to 21531360 its reverse (6313512), we get a palindrome (27844872).

The spelling of 21531360 in words is "twenty-one million, five hundred thirty-one thousand, three hundred sixty".