21930228 has 18 divisors (see below), whose sum is σ = 55434834. Its totient is φ = 7310064.

The previous prime is 21930157. The next prime is 21930269. The reversal of 21930228 is 82203912.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 13704804 + 8225424 = 3702^2 + 2868^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 304551 + ... + 304622.

It is an arithmetic number, because the mean of its divisors is an integer number (3079713).

Almost surely, 2^21930228 is an apocalyptic number.

It is an amenable number.

21930228 is an abundant number, since it is smaller than the sum of its proper divisors (33504606).

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

21930228 is a wasteful number, since it uses less digits than its factorization.

21930228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 609183 (or 609178 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21930228 is about 4682.9721331650. The cubic root of 21930228 is about 279.9074013529.

The spelling of 21930228 in words is "twenty-one million, nine hundred thirty thousand, two hundred twenty-eight".