1111111211221 has 32 divisors (see below), whose sum is σ = 1290587074560. Its totient is φ = 945383980800.

The previous prime is 1111111211173. The next prime is 1111111211237. The reversal of 1111111211221 is 1221121111111.

It is not a de Polignac number, because 1111111211221 - 2¹⁵ = 1111111178453 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1111111211195 and 1111111211204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1111111211251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 49665180 + ... + 49687546.

It is an arithmetic number, because the mean of its divisors is an integer number (40330846080).

Almost surely, 2^{1111111211221} is an apocalyptic number.

1111111211221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1111111211221 is a deficient number, since it is larger than the sum of its proper divisors (179475863339).

1111111211221 is a wasteful number, since it uses less digits than its factorization.

1111111211221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23865.

The product of its digits is 8, while the sum is 16.

Adding to 1111111211221 its reverse (1221121111111), we get a palindrome (2332232322332).

The spelling of 1111111211221 in words is "one trillion, one hundred eleven billion, one hundred eleven million, two hundred eleven thousand, two hundred twenty-one".