21800028 has 48 divisors (see below), whose sum is σ = 53061120. Its totient is φ = 6960000.

The previous prime is 21800017. The next prime is 21800039. The reversal of 21800028 is 82000812.

It is an interprime number because it is at equal distance from previous prime (21800017) and next prime (21800039).

It is a junction number, because it is equal to n+sod(n) for n = 21799977 and 21800013.

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, 28653 + ... + 29403.

It is an arithmetic number, because the mean of its divisors is an integer number (1105440).

Almost surely, 2^21800028 is an apocalyptic number.

It is an amenable number.

21800028 is an abundant number, since it is smaller than the sum of its proper divisors (31261092).

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

21800028 is a wasteful number, since it uses less digits than its factorization.

21800028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 858 (or 856 counting only the distinct ones).

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

The square root of 21800028 is about 4669.0500104411. The cubic root of 21800028 is about 279.3523637251.

The spelling of 21800028 in words is "twenty-one million, eight hundred thousand, twenty-eight".