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18985 = 53797

18985 has 4 divisors (see below), whose sum is σ = 22788. Its totient is φ = 15184.

The previous prime is 18979. The next prime is 19001. The reversal of 18985 is 58981.

18985 = T111 + T112 + T113.

18985 is nontrivially palindromic in base 2.

18985 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2601 + 16384 = 51^2 + 128^2 .

It is a cyclic number.

It is not a de Polignac number, because 18985 - 211 = 16937 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1894 + ... + 1903.

It is an arithmetic number, because the mean of its divisors is an integer number (5697).

218985 is an apocalyptic number.

18985 is the 113-rd centered triangular number.

It is an amenable number.

18985 is a deficient number, since it is larger than the sum of its proper divisors (3803).

18985 is an equidigital number, since it uses as much as digits as its factorization.

18985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3802.

The product of its digits is 2880, while the sum is 31.

The square root of 18985 is about 137.7860660589. The cubic root of 18985 is about 26.6769925289.

The spelling of 18985 in words is "eighteen thousand, nine hundred eighty-five".

Divisors: 1 5 3797 18985