21238028 has 12 divisors (see below), whose sum is σ = 42476112. Its totient is φ = 9102000.

The previous prime is 21237973. The next prime is 21238033. The reversal of 21238028 is 82083212.

21238028 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 21237988 and 21238006.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 379223 + ... + 379278.

It is an arithmetic number, because the mean of its divisors is an integer number (3539676).

Almost surely, 2^21238028 is an apocalyptic number.

21238028 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21238028 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21238028 is a wasteful number, since it uses less digits than its factorization.

21238028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 758512 (or 758510 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 21238028 is about 4608.4734999781. The cubic root of 21238028 is about 276.9308867614.

The spelling of 21238028 in words is "twenty-one million, two hundred thirty-eight thousand, twenty-eight".