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21131 = 1117113
BaseRepresentation
bin101001010001011
31001222122
411022023
51134011
6241455
7115415
oct51213
931878
1021131
1114970
121028b
139806
1479b5
1563db
hex528b

21131 has 8 divisors (see below), whose sum is σ = 24624. Its totient is φ = 17920.

The previous prime is 21121. The next prime is 21139. The reversal of 21131 is 13112.

21131 = T18 + T19 + ... + T50.

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

It is a cyclic number.

It is not a de Polignac number, because 21131 - 26 = 21067 is a prime.

It is a super-2 number, since 2×211312 = 893038322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21139) 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 7 ways as a sum of consecutive naturals, for example, 131 + ... + 243.

It is an arithmetic number, because the mean of its divisors is an integer number (3078).

221131 is an apocalyptic number.

21131 is a deficient number, since it is larger than the sum of its proper divisors (3493).

21131 is a wasteful number, since it uses less digits than its factorization.

21131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141.

The product of its digits is 6, while the sum is 8.

The square root of 21131 is about 145.3650576996. The cubic root of 21131 is about 27.6464909922.

Adding to 21131 its reverse (13112), we get a palindrome (34243).

It can be divided in two parts, 211 and 31, that added together give a palindrome (242).

The spelling of 21131 in words is "twenty-one thousand, one hundred thirty-one".

Divisors: 1 11 17 113 187 1243 1921 21131