21133 has 4 divisors (see below), whose sum is σ = 24160. Its totient is φ = 18108.

The previous prime is 21121. The next prime is 21139. The reversal of 21133 is 33112.

21133 is nontrivially palindromic in base 8.

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.

It is a cyclic number.

It is not a de Polignac number, because 21133 - 2^{5} = 21101 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 (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 3 ways as a sum of consecutive naturals, for example, 1503 + ... + 1516.

It is an arithmetic number, because the mean of its divisors is an integer number (6040).

2^{21133} is an apocalyptic number.

It is an amenable number.

21133 is a deficient number, since it is larger than the sum of its proper divisors (3027).

21133 is an equidigital number, since it uses as much as digits as its factorization.

21133 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3026.

The product of its digits is 18, while the sum is 10.

The square root of 21133 is about 145.3719367691. The cubic root of 21133 is about 27.6473631900.

Subtracting from 21133 its product of digits (18), we obtain a triangular number (21115 = T_{205}).

Adding to 21133 its reverse (33112), we get a palindrome (54245).

It can be divided in two parts, 2113 and 3, that added together give a square (2116 = 46^{2}).

The spelling of 21133 in words is "twenty-one thousand, one hundred thirty-three".

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