20868 has 24 divisors (see below), whose sum is σ = 51072. Its totient is φ = 6624.

The previous prime is 20857. The next prime is 20873. The reversal of 20868 is 86802.

It is a nialpdrome in base 13.

It is an unprimeable number.

20868 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 7 ways as a sum of consecutive naturals, for example, 421 + ... + 467.

It is an arithmetic number, because the mean of its divisors is an integer number (2128).

2²⁰⁸⁶⁸ is an apocalyptic number.

It is an amenable number.

20868 is an abundant number, since it is smaller than the sum of its proper divisors (30204).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25536).

20868 is a wasteful number, since it uses less digits than its factorization.

20868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91 (or 89 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 20868 is about 144.4576062380. The cubic root of 20868 is about 27.5313141913.

Subtracting from 20868 its product of nonzero digits (768), we obtain a triangular number (20100 = T₂₀₀).

It can be divided in two parts, 208 and 68, that added together give a triangular number (276 = T₂₃).

The spelling of 20868 in words is "twenty thousand, eight hundred sixty-eight".