21080028 has 24 divisors (see below), whose sum is σ = 49263760. Its totient is φ = 7015680.

The previous prime is 21080021. The next prime is 21080041. The reversal of 21080028 is 82008012.

It is a junction number, because it is equal to n+sod(n) for n = 21079986 and 21080013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21080021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11238 + ... + 12978.

Almost surely, 2^21080028 is an apocalyptic number.

It is an amenable number.

21080028 is an abundant number, since it is smaller than the sum of its proper divisors (28183732).

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

21080028 is a wasteful number, since it uses less digits than its factorization.

21080028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2757 (or 2755 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

The square root of 21080028 is about 4591.2991625465. The cubic root of 21080028 is about 276.2424355879.

The spelling of 21080028 in words is "twenty-one million, eighty thousand, twenty-eight".