21255228 has 36 divisors (see below), whose sum is σ = 54163200. Its totient is φ = 7027776.

The previous prime is 21255217. The next prime is 21255239. The reversal of 21255228 is 82255212.

It is an interprime number because it is at equal distance from previous prime (21255217) and next prime (21255239).

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2248 + ... + 6896.

Almost surely, 2^21255228 is an apocalyptic number.

It is an amenable number.

21255228 is an abundant number, since it is smaller than the sum of its proper divisors (32907972).

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

21255228 is a wasteful number, since it uses less digits than its factorization.

21255228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4786 (or 4781 counting only the distinct ones).

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

The square root of 21255228 is about 4610.3392499902. The cubic root of 21255228 is about 277.0056257465.

The spelling of 21255228 in words is "twenty-one million, two hundred fifty-five thousand, two hundred twenty-eight".