18685 has 8 divisors (see below), whose sum is σ = 23256. Its totient is φ = 14400.
The previous prime is 18679. The next prime is 18691. The reversal of 18685 is 58681.
It is a happy number.
It is an interprime number because it is at equal distance from previous prime (18679) and next prime (18691).
It can be written as a sum of positive squares in 4 ways, for example, as 10404 + 8281 = 102^2 + 91^2 .
It is a sphenic number, since it is the product of 3 distinct primes.
It is a de Polignac number, because none of the positive numbers 2k-18685 is a prime.
It is a Duffinian number.
It is a nialpdrome in base 12.
It is a congruent number.
It is an unprimeable number.
It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 135 + ... + 235.
It is an arithmetic number, because the mean of its divisors is an integer number (2907).
218685 is an apocalyptic number.
It is an amenable number.
18685 is a deficient number, since it is larger than the sum of its proper divisors (4571).
18685 is a wasteful number, since it uses less digits than its factorization.
18685 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 143.
The product of its digits is 1920, while the sum is 28.
The square root of 18685 is about 136.6930868771. The cubic root of 18685 is about 26.5357296613.
It can be divided in two parts, 18 and 685, that added together give a triangular number (703 = T37).
The spelling of 18685 in words is "eighteen thousand, six hundred eighty-five".
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