221221213 has 2 divisors, whose sum is σ = 221221214. Its totient is φ = 221221212.

The previous prime is 221221127. The next prime is 221221219. The reversal of 221221213 is 312122122.

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., 217769049 + 3452164 = 14757^2 + 1858^2 .

It is a cyclic number.

It is not a de Polignac number, because 221221213 - 2¹³ = 221213021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221221219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110610606 + 110610607.

It is an arithmetic number, because the mean of its divisors is an integer number (110610607).

Almost surely, 2^221221213 is an apocalyptic number.

It is an amenable number.

221221213 is a deficient number, since it is larger than the sum of its proper divisors (1).

221221213 is an equidigital number, since it uses as much as digits as its factorization.

221221213 is an evil number, because the sum of its binary digits is even.

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

The square root of 221221213 is about 14873.5070847464. The cubic root of 221221213 is about 604.7960180213.

Adding to 221221213 its reverse (312122122), we get a palindrome (533343335).

Subtracting 221221213 from its reverse (312122122), we obtain a palindrome (90900909).

The spelling of 221221213 in words is "two hundred twenty-one million, two hundred twenty-one thousand, two hundred thirteen".