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18491 = 11412
BaseRepresentation
bin100100000111011
3221100212
410200323
51042431
6221335
7104624
oct44073
927325
1018491
1112990
12a84b
138555
146a4b
15572b
hex483b

18491 has 6 divisors (see below), whose sum is σ = 20676. Its totient is φ = 16400.

The previous prime is 18481. The next prime is 18493. The reversal of 18491 is 19481.

It is not a de Polignac number, because 18491 - 26 = 18427 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (18493) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 431 + ... + 471.

It is an arithmetic number, because the mean of its divisors is an integer number (3446).

218491 is an apocalyptic number.

18491 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

18491 is a deficient number, since it is larger than the sum of its proper divisors (2185).

18491 is an equidigital number, since it uses as much as digits as its factorization.

With its predecessor (18490) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (93).

18491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93 (or 52 counting only the distinct ones).

The product of its digits is 288, while the sum is 23.

The square root of 18491 is about 135.9816164046. The cubic root of 18491 is about 26.4435728252.

Subtracting 18491 from its reverse (19481), we obtain a triangular number (990 = T44).

The spelling of 18491 in words is "eighteen thousand, four hundred ninety-one".

Divisors: 1 11 41 451 1681 18491