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20005 = 54001
BaseRepresentation
bin100111000100101
31000102221
410320211
51120010
6232341
7112216
oct47045
930387
1020005
1114037
12b6b1
13914b
14740d
155dda
hex4e25

20005 has 4 divisors (see below), whose sum is σ = 24012. Its totient is φ = 16000.

The previous prime is 19997. The next prime is 20011. The reversal of 20005 is 50002.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3364 + 16641 = 58^2 + 129^2 .

It is a sliding number, since 20005 = 5 + 20000 and 1/5 + 1/20000 = 0.20005.

It is not a de Polignac number, because 20005 - 23 = 19997 is a prime.

It is a Duffinian number.

20005 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 20005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (5) 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 3 ways as a sum of consecutive naturals, for example, 1996 + ... + 2005.

It is an arithmetic number, because the mean of its divisors is an integer number (6003).

220005 is an apocalyptic number.

It is an amenable number.

20005 is a deficient number, since it is larger than the sum of its proper divisors (4007).

20005 is an equidigital number, since it uses as much as digits as its factorization.

20005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4006.

The product of its (nonzero) digits is 10, while the sum is 7.

The square root of 20005 is about 141.4390328021. The cubic root of 20005 is about 27.1464379922.

Adding to 20005 its reverse (50002), we get a palindrome (70007).

It can be divided in two parts, 2000 and 5, that multiplied together give a 4-th power (10000 = 104).

The spelling of 20005 in words is "twenty thousand, five".

Divisors: 1 5 4001 20005