1211221121 has 4 divisors (see below), whose sum is σ = 1321332144. Its totient is φ = 1101110100.

The previous prime is 1211221111. The next prime is 1211221129.

1211221121 is nontrivially palindromic in base 10.

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 1211221121 - 2¹⁴ = 1211204737 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1211221096 and 1211221105.

It is not an unprimeable number, because it can be changed into a prime (1211221129) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55055495 + ... + 55055516.

It is an arithmetic number, because the mean of its divisors is an integer number (330333036).

Almost surely, 2^1211221121 is an apocalyptic number.

1211221121 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1211221121 is a deficient number, since it is larger than the sum of its proper divisors (110111023).

1211221121 is a wasteful number, since it uses less digits than its factorization.

1211221121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110111022.

The product of its digits is 16, while the sum is 14.

The square root of 1211221121 is about 34802.6022159263. The cubic root of 1211221121 is about 1065.9605816109.

It can be divided in two parts, 12112 and 21121, that added together give a palindrome (33233).

The spelling of 1211221121 in words is "one billion, two hundred eleven million, two hundred twenty-one thousand, one hundred twenty-one".