21828816 has 120 divisors (see below), whose sum is σ = 66707784. Its totient is φ = 6635520.

The previous prime is 21828803. The next prime is 21828823. The reversal of 21828816 is 61882812.

It can be written as a sum of positive squares in 4 ways, for example, as 13395600 + 8433216 = 3660^2 + 2904^2 .

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

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 90456 + ... + 90696.

Almost surely, 2^21828816 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 21828816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33353892).

21828816 is an abundant number, since it is smaller than the sum of its proper divisors (44878968).

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

21828816 is a wasteful number, since it uses less digits than its factorization.

21828816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309 (or 300 counting only the distinct ones).

The product of its digits is 12288, while the sum is 36.

The square root of 21828816 is about 4672.1318474546. The cubic root of 21828816 is about 279.4752757766.

The spelling of 21828816 in words is "twenty-one million, eight hundred twenty-eight thousand, eight hundred sixteen".