11211211122221 has 4 divisors (see below), whose sum is σ = 12230412133344. Its totient is φ = 10192010111100.

The previous prime is 11211211122127. The next prime is 11211211122227. The reversal of 11211211122221 is 12222111211211.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 11211211122221 - 2²² = 11211206927917 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 11211211122193 and 11211211122202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11211211122227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 509600505545 + ... + 509600505566.

It is an arithmetic number, because the mean of its divisors is an integer number (3057603033336).

Almost surely, 2^{11211211122221} is an apocalyptic number.

11211211122221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11211211122221 is a deficient number, since it is larger than the sum of its proper divisors (1019201011123).

11211211122221 is a wasteful number, since it uses less digits than its factorization.

11211211122221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1019201011122.

The product of its digits is 64, while the sum is 20.

Adding to 11211211122221 its reverse (12222111211211), we get a palindrome (23433322333432).

The spelling of 11211211122221 in words is "eleven trillion, two hundred eleven billion, two hundred eleven million, one hundred twenty-two thousand, two hundred twenty-one".