21228456 has 32 divisors (see below), whose sum is σ = 53357760. Its totient is φ = 7037952.

The previous prime is 21228451. The next prime is 21228469. The reversal of 21228456 is 65482212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21228451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2341 + ... + 6923.

It is an arithmetic number, because the mean of its divisors is an integer number (1667430).

Almost surely, 2^21228456 is an apocalyptic number.

It is an amenable number.

21228456 is an abundant number, since it is smaller than the sum of its proper divisors (32129304).

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

21228456 is a wasteful number, since it uses less digits than its factorization.

21228456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4785 (or 4781 counting only the distinct ones).

The product of its digits is 7680, while the sum is 30.

The square root of 21228456 is about 4607.4348611782. The cubic root of 21228456 is about 276.8892761689.

The spelling of 21228456 in words is "twenty-one million, two hundred twenty-eight thousand, four hundred fifty-six".