21028544 has 28 divisors (see below), whose sum is σ = 42443400. Its totient is φ = 10334208.

The previous prime is 21028517. The next prime is 21028549. The reversal of 21028544 is 44582012.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21028549) 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, 992 + ... + 6560.

Almost surely, 2^21028544 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 21028544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21221700).

21028544 is an abundant number, since it is smaller than the sum of its proper divisors (21414856).

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

21028544 is an equidigital number, since it uses as much as digits as its factorization.

21028544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5640 (or 5630 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 26.

The square root of 21028544 is about 4585.6890430992. The cubic root of 21028544 is about 276.0173622068.

The spelling of 21028544 in words is "twenty-one million, twenty-eight thousand, five hundred forty-four".