21020528 has 30 divisors (see below), whose sum is σ = 42676584. Its totient is φ = 10011232.

The previous prime is 21020521. The next prime is 21020533. The reversal of 21020528 is 82502012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020521) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 87833 + ... + 88071.

Almost surely, 2^21020528 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 21020528, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21338292).

21020528 is an abundant number, since it is smaller than the sum of its proper divisors (21656056).

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

21020528 is an equidigital number, since it uses as much as digits as its factorization.

21020528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 509 (or 264 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 21020528 is about 4584.8149362870. The cubic root of 21020528 is about 275.9822854975.

The spelling of 21020528 in words is "twenty-one million, twenty thousand, five hundred twenty-eight".