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81989 = 163503
BaseRepresentation
bin10100000001000101
311011110122
4110001011
510110424
61431325
7461015
oct240105
9134418
1081989
1156666
123b545
132b41b
1421c45
151945e
hex14045

81989 has 4 divisors (see below), whose sum is σ = 82656. Its totient is φ = 81324.

The previous prime is 81973. The next prime is 82003. The reversal of 81989 is 98918.

It is a happy number.

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 a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 98918 = 249459.

It is a cyclic number.

It is not a de Polignac number, because 81989 - 24 = 81973 is a prime.

It is a super-2 number, since 2×819892 = 13444392242, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 11.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 81989.

It is not an unprimeable number, because it can be changed into a prime (81919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 89 + ... + 414.

It is an arithmetic number, because the mean of its divisors is an integer number (20664).

281989 is an apocalyptic number.

It is an amenable number.

81989 is a deficient number, since it is larger than the sum of its proper divisors (667).

81989 is a wasteful number, since it uses less digits than its factorization.

81989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 666.

The product of its digits is 5184, while the sum is 35.

The square root of 81989 is about 286.3372137882. The cubic root of 81989 is about 43.4428721165.

The spelling of 81989 in words is "eighty-one thousand, nine hundred eighty-nine".

Divisors: 1 163 503 81989