21828856 has 32 divisors (see below), whose sum is σ = 47226240. Its totient is φ = 9265248.

The previous prime is 21828847. The next prime is 21828869. The reversal of 21828856 is 65882812.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4171 + ... + 7813.

It is an arithmetic number, because the mean of its divisors is an integer number (1475820).

Almost surely, 2^21828856 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 21828856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23613120).

21828856 is an abundant number, since it is smaller than the sum of its proper divisors (25397384).

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

21828856 is a wasteful number, since it uses less digits than its factorization.

21828856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3763 (or 3759 counting only the distinct ones).

The product of its digits is 61440, while the sum is 40.

The square root of 21828856 is about 4672.1361281538. The cubic root of 21828856 is about 279.4754464837.

The spelling of 21828856 in words is "twenty-one million, eight hundred twenty-eight thousand, eight hundred fifty-six".