21028896 has 240 divisors, whose sum is σ = 75620160. Its totient is φ = 5598720.

The previous prime is 21028883. The next prime is 21028897. The reversal of 21028896 is 69882012.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21028896.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21028897) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 344706 + ... + 344766.

It is an arithmetic number, because the mean of its divisors is an integer number (315084).

Almost surely, 2^21028896 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 21028896, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37810080).

21028896 is an abundant number, since it is smaller than the sum of its proper divisors (54591264).

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

21028896 is a wasteful number, since it uses less digits than its factorization.

21028896 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109 (or 92 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 21028896 is about 4585.7274232122. The cubic root of 21028896 is about 276.0189022971.

The spelling of 21028896 in words is "twenty-one million, twenty-eight thousand, eight hundred ninety-six".