42221 has 2 divisors, whose sum is σ = 42222.
Its totient is φ = 42220.
The previous prime is 42209. The next prime is 42223. The reversal of 42221 is 12224.
Adding to 42221 its reverse (12224), we get a palindrome (54445).
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 42025 + 196 = 205^2 + 14^2
It is a cyclic number.
It is not a de Polignac number, because 42221 - 26 = 42157 is a prime.
It is a super-2 number, since 2×422212 = 3565225682, which contains 22 as substring.
It is a Sophie Germain prime.
Together with 42223, it forms a pair of twin primes.
It is a Chen prime.
It is a Curzon number.
It is a plaindrome in base 8 and base 14.
It is a nialpdrome in base 10.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (42223) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21110 + 21111.
It is an arithmetic number, because the mean of its divisors is an integer number (21111).
242221 is an apocalyptic number.
It is an amenable number.
42221 is a deficient number, since it is larger than the sum of its proper divisors (1).
42221 is an equidigital number, since it uses as much as digits as its factorization.
42221 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 32, while the sum is 11.
The square root of 42221 is about 205.4774926847.
The cubic root of 42221 is about 34.8211282276.
The spelling of 42221 in words is "forty-two thousand, two hundred twenty-one", and thus it is an iban number.