21228056 has 16 divisors (see below), whose sum is σ = 41087040. Its totient is φ = 10271520.

The previous prime is 21228049. The next prime is 21228059. The reversal of 21228056 is 65082212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21228059) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42551 + ... + 43046.

It is an arithmetic number, because the mean of its divisors is an integer number (2567940).

Almost surely, 2^21228056 is an apocalyptic number.

It is an amenable number.

21228056 is a deficient number, since it is larger than the sum of its proper divisors (19858984).

21228056 is a wasteful number, since it uses less digits than its factorization.

21228056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85634 (or 85630 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 21228056 is about 4607.3914528722. The cubic root of 21228056 is about 276.8875370503.

The spelling of 21228056 in words is "twenty-one million, two hundred twenty-eight thousand, fifty-six".