21020288 has 32 divisors (see below), whose sum is σ = 42333060. Its totient is φ = 10395648.

The previous prime is 21020281. The next prime is 21020299. The reversal of 21020288 is 88202012.

It can be written as a sum of positive squares in 2 ways, for example, as 20866624 + 153664 = 4568^2 + 392^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (21020281) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11570 + ... + 13262.

Almost surely, 2^21020288 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21020288, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21166530).

21020288 is an abundant number, since it is smaller than the sum of its proper divisors (21312772).

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

21020288 is an equidigital number, since it uses as much as digits as its factorization.

With its successor (21020289) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (1804).

21020288 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1804 (or 1792 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 23.

The square root of 21020288 is about 4584.7887628548. The cubic root of 21020288 is about 275.9812351592.

The spelling of 21020288 in words is "twenty-one million, twenty thousand, two hundred eighty-eight".