21552228 has 72 divisors (see below), whose sum is σ = 56565600. Its totient is φ = 6915456.

The previous prime is 21552221. The next prime is 21552233. The reversal of 21552228 is 82225512.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (21552221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 154983 + ... + 155121.

Almost surely, 2^21552228 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 21552228, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28282800).

21552228 is an abundant number, since it is smaller than the sum of its proper divisors (35013372).

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

21552228 is a wasteful number, since it uses less digits than its factorization.

21552228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 281 (or 276 counting only the distinct ones).

The product of its digits is 3200, while the sum is 27.

The square root of 21552228 is about 4642.4377217147. The cubic root of 21552228 is about 278.2898655232.

The spelling of 21552228 in words is "twenty-one million, five hundred fifty-two thousand, two hundred twenty-eight".