1221121121111 has 24 divisors (see below), whose sum is σ = 1361055774624. Its totient is φ = 1093246640640.

The previous prime is 1221121121071. The next prime is 1221121121147. The reversal of 1221121121111 is 1111211211221.

It is not a de Polignac number, because 1221121121111 - 2⁶ = 1221121121047 is a prime.

It is a super-2 number, since 2×1221121121111² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221121121111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221121141111) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 695621 + ... + 1710593.

It is an arithmetic number, because the mean of its divisors is an integer number (56710657276).

Almost surely, 2^{1221121121111} is an apocalyptic number.

1221121121111 is a deficient number, since it is larger than the sum of its proper divisors (139934653513).

1221121121111 is a wasteful number, since it uses less digits than its factorization.

1221121121111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1015211 (or 1015194 counting only the distinct ones).

The product of its digits is 16, while the sum is 17.

Adding to 1221121121111 its reverse (1111211211221), we get a palindrome (2332332332332).

The spelling of 1221121121111 in words is "one trillion, two hundred twenty-one billion, one hundred twenty-one million, one hundred twenty-one thousand, one hundred eleven".