20801 has 8 divisors (see below), whose sum is σ = 23808. Its totient is φ = 18000.

The previous prime is 20789. The next prime is 20807. The reversal of 20801 is 10802.

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

It is a cyclic number.

It is not a de Polignac number, because 20801 - 2¹⁰ = 19777 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (11).

It is a Curzon number.

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (20807) by changing a digit.

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, 311 + ... + 371.

It is an arithmetic number, because the mean of its divisors is an integer number (2976).

2²⁰⁸⁰¹ is an apocalyptic number.

20801 is the 65-th centered decagonal number.

It is an amenable number.

20801 is a deficient number, since it is larger than the sum of its proper divisors (3007).

20801 is a wasteful number, since it uses less digits than its factorization.

20801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 20801 is about 144.2255178531. The cubic root of 20801 is about 27.5018180616.

20801 divided by its sum of digits (11) gives a triangular number (1891 = T₆₁).

Subtracting from 20801 its reverse (10802), we obtain a palindrome (9999).

The spelling of 20801 in words is "twenty thousand, eight hundred one".