1221121211 has 4 divisors (see below), whose sum is σ = 1221334800. Its totient is φ = 1220907624.

The previous prime is 1221121199. The next prime is 1221121259. The reversal of 1221121211 is 1121211221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1121211221 = 13 ⋅86247017.

It is a cyclic number.

It is not a de Polignac number, because 1221121211 - 2²⁶ = 1154012347 is a prime.

It is a super-2 number, since 2×1221121211² = 2982274023908213042, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221120211) 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, 97976 + ... + 109733.

It is an arithmetic number, because the mean of its divisors is an integer number (305333700).

Almost surely, 2^1221121211 is an apocalyptic number.

1221121211 is a deficient number, since it is larger than the sum of its proper divisors (213589).

1221121211 is an equidigital number, since it uses as much as digits as its factorization.

1221121211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213588.

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

The square root of 1221121211 is about 34944.5447960050. The cubic root of 1221121211 is about 1068.8569652479.

Adding to 1221121211 its reverse (1121211221), we get a palindrome (2342332432).

The spelling of 1221121211 in words is "one billion, two hundred twenty-one million, one hundred twenty-one thousand, two hundred eleven".