1221111221221 has 4 divisors (see below), whose sum is σ = 1274203013472.
Its totient is φ = 1168019428972.
The previous prime is 1221111221219. The next prime is 1221111221273. The reversal of 1221111221221 is 1221221111221.
Adding to 1221111221221 its reverse (1221221111221), we get a palindrome (2442332332442).
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 1221111221221 - 21 = 1221111221219 is a prime.
It is a super-2 number, since 2×12211112212212 (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 (1221111221021) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (23) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26545896091 + ... + 26545896136.
It is an arithmetic number, because the mean of its divisors is an integer number (318550753368).
Almost surely, 21221111221221 is an apocalyptic number.
It is an amenable number.
1221111221221 is a deficient number, since it is larger than the sum of its proper divisors (53091792251).
1221111221221 is an equidigital number, since it uses as much as digits as its factorization.
1221111221221 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 53091792250.
The product of its digits is 64, while the sum is 19.
The spelling of 1221111221221 in words is "one trillion, two hundred twenty-one billion, one hundred eleven million, two hundred twenty-one thousand, two hundred twenty-one".