21826728 has 192 divisors, whose sum is σ = 76677120. Its totient is φ = 5443200.

The previous prime is 21826711. The next prime is 21826751. The reversal of 21826728 is 82762812.

It is a happy number.

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 junction number, because it is equal to n+sod(n) for n = 21826692 and 21826701.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 171801 + ... + 171927.

It is an arithmetic number, because the mean of its divisors is an integer number (399360).

Almost surely, 2^21826728 is an apocalyptic number.

21826728 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21826728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38338560).

21826728 is an abundant number, since it is smaller than the sum of its proper divisors (54850392).

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

21826728 is a wasteful number, since it uses less digits than its factorization.

21826728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188 (or 181 counting only the distinct ones).

The product of its digits is 21504, while the sum is 36.

The square root of 21826728 is about 4671.9083895128. The cubic root of 21826728 is about 279.4663645743.

The spelling of 21826728 in words is "twenty-one million, eight hundred twenty-six thousand, seven hundred twenty-eight".