111221221 has 2 divisors, whose sum is σ = 111221222. Its totient is φ = 111221220.

The previous prime is 111221219. The next prime is 111221237. The reversal of 111221221 is 122122111.

It is a m-pointer prime, because the next prime (111221237) can be obtained adding 111221221 to its product of digits (16).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 92428996 + 18792225 = 9614^2 + 4335^2 .

It is a cyclic number.

It is not a de Polignac number, because 111221221 - 2¹ = 111221219 is a prime.

Together with 111221219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (111221251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55610610 + 55610611.

It is an arithmetic number, because the mean of its divisors is an integer number (55610611).

Almost surely, 2^111221221 is an apocalyptic number.

It is an amenable number.

111221221 is a deficient number, since it is larger than the sum of its proper divisors (1).

111221221 is an equidigital number, since it uses as much as digits as its factorization.

111221221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16, while the sum is 13.

The square root of 111221221 is about 10546.1472111857. The cubic root of 111221221 is about 480.9086102796.

Adding to 111221221 its reverse (122122111), we get a palindrome (233343332).

It can be divided in two parts, 11 and 1221221, that multiplied together give a palindrome (13433431).

The spelling of 111221221 in words is "one hundred eleven million, two hundred twenty-one thousand, two hundred twenty-one".