12122221 has 2 divisors, whose sum is σ = 12122222. Its totient is φ = 12122220.

The previous prime is 12122191. The next prime is 12122237. The reversal of 12122221 is 12222121.

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., 9517225 + 2604996 = 3085^2 + 1614^2 .

It is an emirp because it is prime and its reverse (12222121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12122221 - 2⁵ = 12122189 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12122021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6061110 + 6061111.

It is an arithmetic number, because the mean of its divisors is an integer number (6061111).

Almost surely, 2^12122221 is an apocalyptic number.

It is an amenable number.

12122221 is a deficient number, since it is larger than the sum of its proper divisors (1).

12122221 is an equidigital number, since it uses as much as digits as its factorization.

12122221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32, while the sum is 13.

The square root of 12122221 is about 3481.6980052842. The cubic root of 12122221 is about 229.7174918277.

Adding to 12122221 its reverse (12222121), we get a palindrome (24344342).

The spelling of 12122221 in words is "twelve million, one hundred twenty-two thousand, two hundred twenty-one".