21250228 has 6 divisors (see below), whose sum is σ = 37187906. Its totient is φ = 10625112.

The previous prime is 21250217. The next prime is 21250253. The reversal of 21250228 is 82205212.

It can be written as a sum of positive squares in only one way, i.e., 21178404 + 71824 = 4602^2 + 268^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21250199 and 21250208.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2656275 + ... + 2656282.

Almost surely, 2^21250228 is an apocalyptic number.

It is an amenable number.

21250228 is a deficient number, since it is larger than the sum of its proper divisors (15937678).

21250228 is a wasteful number, since it uses less digits than its factorization.

21250228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5312561 (or 5312559 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 21250228 is about 4609.7969586523. The cubic root of 21250228 is about 276.9839034554.

The spelling of 21250228 in words is "twenty-one million, two hundred fifty thousand, two hundred twenty-eight".