1221112221 has 32 divisors (see below), whose sum is σ = 1917520128. Its totient is φ = 676615680.

The previous prime is 1221112201. The next prime is 1221112241. The reversal of 1221112221 is 1222111221.

It is an interprime number because it is at equal distance from previous prime (1221112201) and next prime (1221112241).

It is not a de Polignac number, because 1221112221 - 2¹⁷ = 1220981149 is a prime.

It is a super-2 number, since 2×1221112221² = 2982230112551105682, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1221112221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221112201) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 240691 + ... + 245711.

It is an arithmetic number, because the mean of its divisors is an integer number (59922504).

Almost surely, 2^1221112221 is an apocalyptic number.

It is an amenable number.

1221112221 is a deficient number, since it is larger than the sum of its proper divisors (696407907).

1221112221 is a wasteful number, since it uses less digits than its factorization.

1221112221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5381.

The product of its digits is 32, while the sum is 15.

The square root of 1221112221 is about 34944.4161633872. The cubic root of 1221112221 is about 1068.8543422357.

Adding to 1221112221 its reverse (1222111221), we get a palindrome (2443223442).

The spelling of 1221112221 in words is "one billion, two hundred twenty-one million, one hundred twelve thousand, two hundred twenty-one".