21713 has 2 divisors, whose sum is σ = 21714. Its totient is φ = 21712.
The previous prime is 21701. The next prime is 21727. The reversal of 21713 is 31712.
It is an a-pointer prime, because the next prime (21727) can be obtained adding 21713 to its sum of digits (14).
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 16384 + 5329 = 128^2 + 73^2 .
It is a cyclic number.
It is not a de Polignac number, because 21713 - 26 = 21649 is a prime.
It is a Sophie Germain prime.
It is a Curzon number.
It is a plaindrome in base 15.
It is not a weakly prime, because it can be changed into another prime (21773) 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 as a sum of consecutive naturals, namely, 10856 + 10857.
It is an arithmetic number, because the mean of its divisors is an integer number (10857).
221713 is an apocalyptic number.
It is an amenable number.
21713 is a deficient number, since it is larger than the sum of its proper divisors (1).
21713 is an equidigital number, since it uses as much as digits as its factorization.
21713 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 42, while the sum is 14.
The square root of 21713 is about 147.3533168951. The cubic root of 21713 is about 27.8980133304.
Subtracting 21713 from its reverse (31712), we obtain a palindrome (9999).
The spelling of 21713 in words is "twenty-one thousand, seven hundred thirteen".
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