21313 has 2 divisors, whose sum is σ = 21314. Its totient is φ = 21312.

The previous prime is 21283. The next prime is 21317. The reversal of 21313 is 31312.

21313 is nontrivially palindromic in base 12.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16129 + 5184 = 127^2 + 72^2 .

It is a cyclic number.

It is not a de Polignac number, because 21313 - 2¹³ = 13121 is a prime.

It is a nialpdrome in base 9.

It is a self number, because there is not a number n which added to its sum of digits gives 21313.

It is not a weakly prime, because it can be changed into another prime (21317) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656 + 10657.

It is an arithmetic number, because the mean of its divisors is an integer number (10657).

2²¹³¹³ is an apocalyptic number.

It is an amenable number.

21313 is a deficient number, since it is larger than the sum of its proper divisors (1).

21313 is an equidigital number, since it uses as much as digits as its factorization.

21313 is an evil number, because the sum of its binary digits is even.

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

The square root of 21313 is about 145.9897256659. The cubic root of 21313 is about 27.7256367069.

Adding to 21313 its reverse (31312), we get a palindrome (52625).

Subtracting 21313 from its reverse (31312), we obtain a palindrome (9999).

The spelling of 21313 in words is "twenty-one thousand, three hundred thirteen".