220021 has 2 divisors, whose sum is σ = 220022.
Its totient is φ = 220020.
The previous prime is 220019. The next prime is 220057. The reversal of 220021 is 120022.
It is a happy number.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 207025 + 12996 = 455^2 + 114^2
It is a cyclic number.
It is not a de Polignac number, because 220021 - 21 = 220019 is a prime.
Together with 220019, it forms a pair of twin primes.
It is a magnanimous number.
It is a junction number, because it is equal to n+sod(n) for n = 219986 and 220013.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (220421) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110010 + 110011.
It is an arithmetic number, because the mean of its divisors is an integer number (110011).
2220021 is an apocalyptic number.
It is an amenable number.
220021 is a deficient number, since it is larger than the sum of its proper divisors (1).
220021 is an equidigital number, since it uses as much as digits as its factorization.
220021 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 8, while the sum is 7.
The square root of 220021 is about 469.0639615234.
The cubic root of 220021 is about 60.3700281103.
Adding to 220021 its reverse (120022), we get a palindrome (340043).
Subtracting from 220021 its reverse (120022), we obtain a palindrome (99999).
The spelling of 220021 in words is "two hundred twenty thousand, twenty-one", and thus it is an iban number.