221213221 has 2 divisors, whose sum is σ = 221213222. Its totient is φ = 221213220.

The previous prime is 221213183. The next prime is 221213233. The reversal of 221213221 is 122312122.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155376225 + 65836996 = 12465^2 + 8114^2 .

It is a cyclic number.

It is not a de Polignac number, because 221213221 - 2⁷ = 221213093 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 221213195 and 221213204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221213261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110606610 + 110606611.

It is an arithmetic number, because the mean of its divisors is an integer number (110606611).

Almost surely, 2^221213221 is an apocalyptic number.

It is an amenable number.

221213221 is a deficient number, since it is larger than the sum of its proper divisors (1).

221213221 is an equidigital number, since it uses as much as digits as its factorization.

221213221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 96, while the sum is 16.

The square root of 221213221 is about 14873.2384167000. The cubic root of 221213221 is about 604.7887348319.

Adding to 221213221 its reverse (122312122), we get a palindrome (343525343).

The spelling of 221213221 in words is "two hundred twenty-one million, two hundred thirteen thousand, two hundred twenty-one".