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28391 = 112989
BaseRepresentation
bin110111011100111
31102221112
412323213
51402031
6335235
7145526
oct67347
942845
1028391
111a370
121451b
13cbcc
14a4bd
15862b
hex6ee7

28391 has 8 divisors (see below), whose sum is σ = 32400. Its totient is φ = 24640.

The previous prime is 28387. The next prime is 28393. The reversal of 28391 is 19382.

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

It is not a de Polignac number, because 28391 - 22 = 28387 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28393) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 275 + ... + 363.

It is an arithmetic number, because the mean of its divisors is an integer number (4050).

228391 is an apocalyptic number.

28391 is a deficient number, since it is larger than the sum of its proper divisors (4009).

28391 is a wasteful number, since it uses less digits than its factorization.

28391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129.

The product of its digits is 432, while the sum is 23.

The square root of 28391 is about 168.4962907604. The cubic root of 28391 is about 30.5065828307.

Subtracting from 28391 its reverse (19382), we obtain a palindrome (9009).

The spelling of 28391 in words is "twenty-eight thousand, three hundred ninety-one".

Divisors: 1 11 29 89 319 979 2581 28391