21028128 has 48 divisors (see below), whose sum is σ = 60219936. Its totient is φ = 6371840.

The previous prime is 21028127. The next prime is 21028153. The reversal of 21028128 is 82182012.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a junction number, because it is equal to n+sod(n) for n = 21028098 and 21028107.

It is not an unprimeable number, because it can be changed into a prime (21028123) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8901 + ... + 11012.

It is an arithmetic number, because the mean of its divisors is an integer number (1254582).

Almost surely, 2^21028128 is an apocalyptic number.

It is an amenable number.

21028128 is an abundant number, since it is smaller than the sum of its proper divisors (39191808).

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

21028128 is a wasteful number, since it uses less digits than its factorization.

21028128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19937 (or 19929 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 21028128 is about 4585.6436843697. The cubic root of 21028128 is about 276.0155420779.

The spelling of 21028128 in words is "twenty-one million, twenty-eight thousand, one hundred twenty-eight".