21269 has 2 divisors, whose sum is σ = 21270.
Its totient is φ = 21268.
The previous prime is 21247. The next prime is 21277. The reversal of 21269 is 96212.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 18769 + 2500 = 137^2 + 50^2
It is a cyclic number.
It is not a de Polignac number, because 21269 - 28 = 21013 is a prime.
It is a super-2 number, since 2×212692 = 904740722, which contains 22 as substring.
It is a Chen prime.
It is a self number, because there is not a number n which added to its sum of digits gives 21269.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (21169) 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, 10634 + 10635.
It is an arithmetic number, because the mean of its divisors is an integer number (10635).
221269 is an apocalyptic number.
It is an amenable number.
21269 is a deficient number, since it is larger than the sum of its proper divisors (1).
21269 is an equidigital number, since it uses as much as digits as its factorization.
21269 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 216, while the sum is 20.
The square root of 21269 is about 145.8389522727.
The cubic root of 21269 is about 27.7065440016.
The spelling of 21269 in words is "twenty-one thousand, two hundred sixty-nine".