21827728 has 40 divisors (see below), whose sum is σ = 48231288. Its totient is φ = 9480192.

The previous prime is 21827723. The next prime is 21827753. The reversal of 21827728 is 82772812.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 144 + 21827584 = 12^2 + 4672^2 .

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21827723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 450 + ... + 6622.

Almost surely, 2^21827728 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 21827728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24115644).

21827728 is an abundant number, since it is smaller than the sum of its proper divisors (26403560).

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

21827728 is a wasteful number, since it uses less digits than its factorization.

21827728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6211 (or 6205 counting only the distinct ones).

The product of its digits is 25088, while the sum is 37.

The square root of 21827728 is about 4672.0154109335. The cubic root of 21827728 is about 279.4706324624.

The spelling of 21827728 in words is "twenty-one million, eight hundred twenty-seven thousand, seven hundred twenty-eight".