21323 has 2 divisors, whose sum is σ = 21324. Its totient is φ = 21322.

The previous prime is 21319. The next prime is 21341. The reversal of 21323 is 32312.

Subtracting from 21323 its sum of digits (11), we obtain a palindrome (21312).

Adding to 21323 its reverse (32312), we get a palindrome (53635).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21323 - 2^{2} = 21319 is a prime.

It is an Ulam number.

It is a d-powerful number, because it can be written as **2**^{3} + **1** + **3**^{8} + **2**^{13} + **3**^{8} .

It is a nialpdrome in base 9.

It is not a weakly prime, because it can be changed into another prime (21313) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10661 + 10662.

It is an arithmetic number, because the mean of its divisors is an integer number (10662).

2^{21323} is an apocalyptic number.

21323 is a deficient number, since it is larger than the sum of its proper divisors (1).

21323 is an equidigital number, since it uses as much as digits as its factorization.

21323 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36, while the sum is 11.

The square root of 21323 is about 146.0239706350. The cubic root of 21323 is about 27.7299722926.

The spelling of 21323 in words is "twenty-one thousand, three hundred twenty-three", and thus it is an iban number.

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