1221211112221 has 4 divisors (see below), whose sum is σ = 1221213630492. Its totient is φ = 1221208593952.

The previous prime is 1221211112201. The next prime is 1221211112249. The reversal of 1221211112221 is 1222111121221.

It is a happy number.

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 600446763225 + 620764348996 = 774885^2 + 787886^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221211112221 - 2²¹ = 1221209015069 is a prime.

It is a super-2 number, since 2×1221211112221² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221211112201) 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, 275680 + ... + 1586953.

It is an arithmetic number, because the mean of its divisors is an integer number (305303407623).

Almost surely, 2^{1221211112221} is an apocalyptic number.

It is an amenable number.

1221211112221 is a deficient number, since it is larger than the sum of its proper divisors (2518271).

1221211112221 is an equidigital number, since it uses as much as digits as its factorization.

1221211112221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2518270.

The product of its digits is 64, while the sum is 19.

Adding to 1221211112221 its reverse (1222111121221), we get a palindrome (2443322233442).

The spelling of 1221211112221 in words is "one trillion, two hundred twenty-one billion, two hundred eleven million, one hundred twelve thousand, two hundred twenty-one".