21047028 has 24 divisors (see below), whose sum is σ = 49563360. Its totient is φ = 6950880.

The previous prime is 21047017. The next prime is 21047051. The reversal of 21047028 is 82074012.

It is a junction number, because it is equal to n+sod(n) for n = 21046989 and 21047007.

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 7 ways as a sum of consecutive naturals, for example, 6738 + ... + 9353.

It is an arithmetic number, because the mean of its divisors is an integer number (2065140).

Almost surely, 2^21047028 is an apocalyptic number.

It is an amenable number.

21047028 is an abundant number, since it is smaller than the sum of its proper divisors (28516332).

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

21047028 is a wasteful number, since it uses less digits than its factorization.

21047028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16207 (or 16205 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 21047028 is about 4587.7040009137. The cubic root of 21047028 is about 276.0982112154.

The spelling of 21047028 in words is "twenty-one million, forty-seven thousand, twenty-eight".