221230021 has 2 divisors, whose sum is σ = 221230022. Its totient is φ = 221230020.

The previous prime is 221230019. The next prime is 221230057. The reversal of 221230021 is 120032122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 152522500 + 68707521 = 12350^2 + 8289^2 .

It is a cyclic number.

It is not a de Polignac number, because 221230021 - 2¹ = 221230019 is a prime.

Together with 221230019, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 221229983 and 221230010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221230001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110615010 + 110615011.

It is an arithmetic number, because the mean of its divisors is an integer number (110615011).

Almost surely, 2^221230021 is an apocalyptic number.

It is an amenable number.

221230021 is a deficient number, since it is larger than the sum of its proper divisors (1).

221230021 is an equidigital number, since it uses as much as digits as its factorization.

221230021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 221230021 is about 14873.8031787435. The cubic root of 221230021 is about 604.8040446365.

Adding to 221230021 its reverse (120032122), we get a palindrome (341262143).

The spelling of 221230021 in words is "two hundred twenty-one million, two hundred thirty thousand, twenty-one".