21028810 has 32 divisors (see below), whose sum is σ = 42083712. Its totient is φ = 7500480.

The previous prime is 21028771. The next prime is 21028823. The reversal of 21028810 is 1882012.

It is a super-2 number, since 2×21028810² = 884421700032200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 4027 + ... + 7633.

It is an arithmetic number, because the mean of its divisors is an integer number (1315116).

Almost surely, 2^21028810 is an apocalyptic number.

21028810 is an abundant number, since it is smaller than the sum of its proper divisors (21054902).

21028810 is a wasteful number, since it uses less digits than its factorization.

21028810 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3678.

The product of its (nonzero) digits is 256, while the sum is 22.

The square root of 21028810 is about 4585.7180462824. The cubic root of 21028810 is about 276.0185260266.

The spelling of 21028810 in words is "twenty-one million, twenty-eight thousand, eight hundred ten".