21055224 has 16 divisors (see below), whose sum is σ = 52638120. Its totient is φ = 7018400.

The previous prime is 21055217. The next prime is 21055259. The reversal of 21055224 is 42255012.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21055224.

It is a congruent number.

It is an unprimeable number.

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, 438627 + ... + 438674.

Almost surely, 2^21055224 is an apocalyptic number.

21055224 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21055224 is an abundant number, since it is smaller than the sum of its proper divisors (31582896).

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

21055224 is a wasteful number, since it uses less digits than its factorization.

21055224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 877310 (or 877306 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 21055224 is about 4588.5971712496. The cubic root of 21055224 is about 276.1340453684.

The spelling of 21055224 in words is "twenty-one million, fifty-five thousand, two hundred twenty-four".