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18689 = 111699
BaseRepresentation
bin100100100000001
3221122012
410210001
51044224
6222305
7105326
oct44401
927565
1018689
1113050
12a995
138678
146b4d
15580e
hex4901

18689 has 4 divisors (see below), whose sum is σ = 20400. Its totient is φ = 16980.

The previous prime is 18679. The next prime is 18691. The reversal of 18689 is 98681.

Added to its reverse (98681) it gives a triangular number (117370 = T484).

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 98681 = 118971.

It is a cyclic number.

It is not a de Polignac number, because 18689 - 28 = 18433 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a nialpdrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (18679) 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, 839 + ... + 860.

It is an arithmetic number, because the mean of its divisors is an integer number (5100).

It is a Proth number, since it is equal to 73 ⋅ 28 + 1 and 73 < 28.

218689 is an apocalyptic number.

It is an amenable number.

18689 is a deficient number, since it is larger than the sum of its proper divisors (1711).

18689 is a wasteful number, since it uses less digits than its factorization.

18689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1710.

The product of its digits is 3456, while the sum is 32.

The square root of 18689 is about 136.7077174120. The cubic root of 18689 is about 26.5376230757.

Adding to 18689 its sum of digits (32), we get a triangular number (18721 = T193).

Adding to 18689 its reverse (98681), we get a triangular number (117370 = T484).

It can be divided in two parts, 18 and 689, that added together give a palindrome (707).

The spelling of 18689 in words is "eighteen thousand, six hundred eighty-nine".

Divisors: 1 11 1699 18689