121211221 has 2 divisors, whose sum is σ = 121211222. Its totient is φ = 121211220.

The previous prime is 121211183. The next prime is 121211227. The reversal of 121211221 is 122112121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 118919025 + 2292196 = 10905^2 + 1514^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-121211221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121211227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60605610 + 60605611.

It is an arithmetic number, because the mean of its divisors is an integer number (60605611).

Almost surely, 2^121211221 is an apocalyptic number.

It is an amenable number.

121211221 is a deficient number, since it is larger than the sum of its proper divisors (1).

121211221 is an equidigital number, since it uses as much as digits as its factorization.

121211221 is an evil number, because the sum of its binary digits is even.

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

The square root of 121211221 is about 11009.5967682745. The cubic root of 121211221 is about 494.8963779967.

Adding to 121211221 its reverse (122112121), we get a palindrome (243323342).

It can be divided in two parts, 12121 and 1221, that multiplied together give a palindrome (14799741).

The spelling of 121211221 in words is "one hundred twenty-one million, two hundred eleven thousand, two hundred twenty-one".