21211 has 2 divisors, whose sum is σ = 21212.
Its totient is φ = 21210.
The previous prime is 21193. The next prime is 21221. The reversal of 21211 is 11212.
It is a strong prime.
It is a cyclic number.
It is not a de Polignac number, because 21211 - 25 = 21179 is a prime.
21211 is a lucky number.
It is a nialpdrome in base 15.
It is a junction number, because it is equal to n+sod(n) for n = 21194 and 21203.
It is not a weakly prime, because it can be changed into another prime (21221) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605 + 10606.
It is an arithmetic number, because the mean of its divisors is an integer number (10606).
221211 is an apocalyptic number.
21211 is a deficient number, since it is larger than the sum of its proper divisors (1).
21211 is an equidigital number, since it uses as much as digits as its factorization.
21211 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 4, while the sum is 7.
The square root of 21211 is about 145.6399670420.
The cubic root of 21211 is about 27.6813360699.
Adding to 21211 its reverse (11212), we get a palindrome (32423).
Subtracting from 21211 its reverse (11212), we obtain a palindrome (9999).
It can be divided in two parts, 212 and 11, that multiplied together give a palindrome (2332).
The spelling of 21211 in words is "twenty-one thousand, two hundred eleven", and thus it is an iban number.