20985 has 8 divisors (see below), whose sum is σ = 33600. Its totient is φ = 11184.

The previous prime is 20983. The next prime is 21001. The reversal of 20985 is 58902.

20985 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 20985 - 2¹ = 20983 is a prime.

20985 is strictly pandigital in base 6.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 20985.

It is not an unprimeable number, because it can be changed into a prime (20981) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 685 + ... + 714.

It is an arithmetic number, because the mean of its divisors is an integer number (4200).

2²⁰⁹⁸⁵ is an apocalyptic number.

It is an amenable number.

20985 is a deficient number, since it is larger than the sum of its proper divisors (12615).

20985 is a wasteful number, since it uses less digits than its factorization.

20985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1407.

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 20985 is about 144.8620032997. The cubic root of 20985 is about 27.5826713321.

The spelling of 20985 in words is "twenty thousand, nine hundred eighty-five".