21028206 has 8 divisors (see below), whose sum is σ = 42056424. Its totient is φ = 7009400.

The previous prime is 21028181. The next prime is 21028211. The reversal of 21028206 is 60282012.

It is a sphenic number, since it is the product of 3 distinct primes.

21028206 is an admirable number.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 1752345 + ... + 1752356.

It is an arithmetic number, because the mean of its divisors is an integer number (5257053).

Almost surely, 2^21028206 is an apocalyptic number.

21028206 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.

21028206 is a wasteful number, since it uses less digits than its factorization.

21028206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3504706.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21028206 is about 4585.6521891657. The cubic root of 21028206 is about 276.0158833539.

The spelling of 21028206 in words is "twenty-one million, twenty-eight thousand, two hundred six".