21728960 has 56 divisors (see below), whose sum is σ = 56455056. Its totient is φ = 7900160.

The previous prime is 21728947. The next prime is 21728963. The reversal of 21728960 is 6982712.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21728960.

It is not an unprimeable number, because it can be changed into a prime (21728963) 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 7 ways as a sum of consecutive naturals, for example, 434 + ... + 6606.

It is an arithmetic number, because the mean of its divisors is an integer number (1008126).

Almost surely, 2^21728960 is an apocalyptic number.

21728960 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 21728960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28227528).

21728960 is an abundant number, since it is smaller than the sum of its proper divisors (34726096).

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

21728960 is a wasteful number, since it uses less digits than its factorization.

21728960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6201 (or 6191 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 21728960 is about 4661.4332559847. The cubic root of 21728960 is about 279.0484707435.

The spelling of 21728960 in words is "twenty-one million, seven hundred twenty-eight thousand, nine hundred sixty".