21328560 has 120 divisors (see below), whose sum is σ = 78169104. Its totient is φ = 5168640.

The previous prime is 21328537. The next prime is 21328561. The reversal of 21328560 is 6582312.

It is a tau number, because it is divible by the number of its divisors (120).

It is not an unprimeable number, because it can be changed into a prime (21328561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6574 + ... + 9266.

Almost surely, 2^21328560 is an apocalyptic number.

21328560 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 21328560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39084552).

21328560 is an abundant number, since it is smaller than the sum of its proper divisors (56840544).

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

21328560 is a wasteful number, since it uses less digits than its factorization.

21328560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2723 (or 2714 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 21328560 is about 4618.2853961183. The cubic root of 21328560 is about 277.3238229193.

The spelling of 21328560 in words is "twenty-one million, three hundred twenty-eight thousand, five hundred sixty".