21530560 has 56 divisors (see below), whose sum is σ = 52157376. Its totient is φ = 8463360.

The previous prime is 21530543. The next prime is 21530563. The reversal of 21530560 is 6503512.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530563) 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, 18969 + ... + 20071.

Almost surely, 2^21530560 is an apocalyptic number.

21530560 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 21530560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26078688).

21530560 is an abundant number, since it is smaller than the sum of its proper divisors (30626816).

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

21530560 is a wasteful number, since it uses less digits than its factorization.

21530560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1181 (or 1171 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 22.

The square root of 21530560 is about 4640.1034471227. The cubic root of 21530560 is about 278.1965726669.

The spelling of 21530560 in words is "twenty-one million, five hundred thirty thousand, five hundred sixty".