21528228 has 24 divisors (see below), whose sum is σ = 51591232. Its totient is φ = 6981984.

The previous prime is 21528223. The next prime is 21528257. The reversal of 21528228 is 82282512.

It is a junction number, because it is equal to n+sod(n) for n = 21528195 and 21528204.

It is not an unprimeable number, because it can be changed into a prime (21528223) 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, 23800 + ... + 24687.

Almost surely, 2^21528228 is an apocalyptic number.

It is an amenable number.

21528228 is an abundant number, since it is smaller than the sum of its proper divisors (30063004).

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

21528228 is a wasteful number, since it uses less digits than its factorization.

21528228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48531 (or 48529 counting only the distinct ones).

The product of its digits is 5120, while the sum is 30.

The square root of 21528228 is about 4639.8521528169. The cubic root of 21528228 is about 278.1865283728.

The spelling of 21528228 in words is "twenty-one million, five hundred twenty-eight thousand, two hundred twenty-eight".