21044028 has 48 divisors (see below), whose sum is σ = 53222400. Its totient is φ = 6445824.

The previous prime is 21044003. The next prime is 21044047. The reversal of 21044028 is 82044012.

It is a super-2 number, since 2×21044028² = 885702228929568, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21043995 and 21044013.

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 15 ways as a sum of consecutive naturals, for example, 7573 + ... + 9971.

It is an arithmetic number, because the mean of its divisors is an integer number (1108800).

Almost surely, 2^21044028 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21044028, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26611200).

21044028 is an abundant number, since it is smaller than the sum of its proper divisors (32178372).

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

21044028 is a wasteful number, since it uses less digits than its factorization.

21044028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2466 (or 2464 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 21.

The square root of 21044028 is about 4587.3770283246. The cubic root of 21044028 is about 276.0850924353.

The spelling of 21044028 in words is "twenty-one million, forty-four thousand, twenty-eight".