20863 has 4 divisors (see below), whose sum is σ = 21568. Its totient is φ = 20160.

The previous prime is 20857. The next prime is 20873. The reversal of 20863 is 36802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 36802 = 2 ⋅18401.

It is a cyclic number.

It is not a de Polignac number, because 20863 - 2¹³ = 12671 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20863.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20873) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 306 + ... + 367.

It is an arithmetic number, because the mean of its divisors is an integer number (5392).

2²⁰⁸⁶³ is an apocalyptic number.

20863 is a deficient number, since it is larger than the sum of its proper divisors (705).

20863 is an equidigital number, since it uses as much as digits as its factorization.

20863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 704.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 20863 is about 144.4402990858. The cubic root of 20863 is about 27.5291151694.

The spelling of 20863 in words is "twenty thousand, eight hundred sixty-three".