20928 has 28 divisors (see below), whose sum is σ = 55880. Its totient is φ = 6912.

The previous prime is 20921. The next prime is 20929. The reversal of 20928 is 82902.

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20921) by changing a digit.

20928 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 (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 138 + ... + 246.

2²⁰⁹²⁸ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27940).

20928 is an abundant number, since it is smaller than the sum of its proper divisors (34952).

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

20928 is a wasteful number, since it uses less digits than its factorization.

20928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124 (or 114 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 20928 is about 144.6651305602. The cubic root of 20928 is about 27.5576750981.

The spelling of 20928 in words is "twenty thousand, nine hundred twenty-eight".