221221243 has 2 divisors, whose sum is σ = 221221244. Its totient is φ = 221221242.

The previous prime is 221221219. The next prime is 221221249. The reversal of 221221243 is 342122122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221221243 - 2²¹ = 219124091 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221221243.

It is not a weakly prime, because it can be changed into another prime (221221249) 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, 110610621 + 110610622.

It is an arithmetic number, because the mean of its divisors is an integer number (110610622).

Almost surely, 2^221221243 is an apocalyptic number.

221221243 is a deficient number, since it is larger than the sum of its proper divisors (1).

221221243 is an equidigital number, since it uses as much as digits as its factorization.

221221243 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 384, while the sum is 19.

The square root of 221221243 is about 14873.5080932509. The cubic root of 221221243 is about 604.7960453603.

Adding to 221221243 its reverse (342122122), we get a palindrome (563343365).

The spelling of 221221243 in words is "two hundred twenty-one million, two hundred twenty-one thousand, two hundred forty-three".