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BaseRepresentation
bin110110101101101
31102102112
412311231
51344023
6333405
7144446
oct66555
942375
1028013
111a057
1214265
13c99b
14a2cd
158478
hex6d6d

28013 has 4 divisors (see below), whose sum is σ = 28380. Its totient is φ = 27648.

The previous prime is 28001. The next prime is 28019. The reversal of 28013 is 31082.

Adding to 28013 its reverse (31082), we get a palindrome (59095).

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 31082 = 215541.

It can be written as a sum of positive squares in 2 ways, for example, as 24649 + 3364 = 157^2 + 58^2 .

It is a cyclic number.

It is not a de Polignac number, because 28013 - 24 = 27997 is a prime.

It is a Duffinian number.

28013 is an undulating number in base 16.

It is a plaindrome in base 7.

It is a nialpdrome in base 8.

It is a zygodrome in base 8.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28019) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20 + ... + 237.

It is an arithmetic number, because the mean of its divisors is an integer number (7095).

228013 is an apocalyptic number.

It is an amenable number.

28013 is a deficient number, since it is larger than the sum of its proper divisors (367).

28013 is a wasteful number, since it uses less digits than its factorization.

28013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 28013 is about 167.3708457289. The cubic root of 28013 is about 30.3705884746.

The spelling of 28013 in words is "twenty-eight thousand, thirteen".

Divisors: 1 109 257 28013