221211122211221 has 4 divisors (see below), whose sum is σ = 221211162014700. Its totient is φ = 221211082407744.

The previous prime is 221211122211187. The next prime is 221211122211223. The reversal of 221211122211221 is 122112221112122.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 57722933148721 + 163488189062500 = 7597561^2 + 12786250^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221211122211221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221211122211223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9884786 + ... + 23240723.

It is an arithmetic number, because the mean of its divisors is an integer number (55302790503675).

Almost surely, 2^{221211122211221} is an apocalyptic number.

It is an amenable number.

221211122211221 is a deficient number, since it is larger than the sum of its proper divisors (39803479).

221211122211221 is an equidigital number, since it uses as much as digits as its factorization.

221211122211221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39803478.

The product of its digits is 256, while the sum is 23.

Adding to 221211122211221 its reverse (122112221112122), we get a palindrome (343323343323343).

The spelling of 221211122211221 in words is "two hundred twenty-one trillion, two hundred eleven billion, one hundred twenty-two million, two hundred eleven thousand, two hundred twenty-one".