21055128 has 16 divisors (see below), whose sum is σ = 52637880. Its totient is φ = 7018368.

The previous prime is 21055123. The next prime is 21055141. The reversal of 21055128 is 82155012.

It is a Harshad number since it is a multiple of its sum of digits (24), and also a Moran number because the ratio is a prime number: 877297 = 21055128 / (2 + 1 + 0 + 5 + 5 + 1 + 2 + 8).

It is a junction number, because it is equal to n+sod(n) for n = 21055098 and 21055107.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 438625 + ... + 438672.

Almost surely, 2^21055128 is an apocalyptic number.

It is an amenable number.

21055128 is an abundant number, since it is smaller than the sum of its proper divisors (31582752).

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

21055128 is a wasteful number, since it uses less digits than its factorization.

21055128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 877306 (or 877302 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 24.

The square root of 21055128 is about 4588.5867105243. The cubic root of 21055128 is about 276.1336256957.

The spelling of 21055128 in words is "twenty-one million, fifty-five thousand, one hundred twenty-eight".