20828 has 12 divisors (see below), whose sum is σ = 37632. Its totient is φ = 10080.

The previous prime is 20809. The next prime is 20849. The reversal of 20828 is 82802.

It is a nialpdrome in base 13.

It is a congruent number.

It is an unprimeable number.

20828 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 101 + ... + 227.

It is an arithmetic number, because the mean of its divisors is an integer number (3136).

2²⁰⁸²⁸ is an apocalyptic number.

It is an amenable number.

20828 is a deficient number, since it is larger than the sum of its proper divisors (16804).

20828 is a wasteful number, since it uses less digits than its factorization.

20828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172 (or 170 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 20828 is about 144.3190909062. The cubic root of 20828 is about 27.5137121699.

It can be divided in two parts, 20 and 828, that added together give a palindrome (848).

The spelling of 20828 in words is "twenty thousand, eight hundred twenty-eight".