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18031 = 131973
BaseRepresentation
bin100011001101111
3220201211
410121233
51034111
6215251
7103366
oct43157
926654
1018031
1112602
12a527
138290
1467dd
155521
hex466f

18031 has 8 divisors (see below), whose sum is σ = 20720. Its totient is φ = 15552.

The previous prime is 18013. The next prime is 18041. The reversal of 18031 is 13081.

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

It is a 6-Lehmer number, since φ(18031) divides (18031-1)6.

It is a cyclic number.

It is not a de Polignac number, because 18031 - 27 = 17903 is a prime.

It is a super-2 number, since 2×180312 = 650233922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a Duffinian number.

It is a plaindrome in base 14 and base 16.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18041) 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, 211 + ... + 283.

It is an arithmetic number, because the mean of its divisors is an integer number (2590).

218031 is an apocalyptic number.

18031 is a deficient number, since it is larger than the sum of its proper divisors (2689).

18031 is a wasteful number, since it uses less digits than its factorization.

18031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 18031 is about 134.2795591295. The cubic root of 18031 is about 26.2224503103. Note that the first 3 decimals are identical.

Subtracting from 18031 its reverse (13081), we obtain a triangular number (4950 = T99).

The spelling of 18031 in words is "eighteen thousand, thirty-one".

Divisors: 1 13 19 73 247 949 1387 18031