11211121221 has 32 divisors (see below), whose sum is σ = 15432270336. Its totient is φ = 7235136000.

The previous prime is 11211121199. The next prime is 11211121277. The reversal of 11211121221 is 12212111211.

It is a happy number.

It is not a de Polignac number, because 11211121221 - 2⁶ = 11211121157 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 11211121221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11211123221) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10566031 + ... + 10567091.

It is an arithmetic number, because the mean of its divisors is an integer number (482258448).

Almost surely, 2^11211121221 is an apocalyptic number.

It is an amenable number.

11211121221 is a deficient number, since it is larger than the sum of its proper divisors (4221149115).

11211121221 is a wasteful number, since it uses less digits than its factorization.

11211121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1693.

The product of its digits is 16, while the sum is 15.

Adding to 11211121221 its reverse (12212111211), we get a palindrome (23423232432).

The spelling of 11211121221 in words is "eleven billion, two hundred eleven million, one hundred twenty-one thousand, two hundred twenty-one".