1221120221 has 4 divisors (see below), whose sum is σ = 1221939612. Its totient is φ = 1220300832.

The previous prime is 1221120211. The next prime is 1221120233. The reversal of 1221120221 is 1220211221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1220211221 = 29 ⋅42076249.

It can be written as a sum of positive squares in 2 ways, for example, as 701508196 + 519612025 = 26486^2 + 22795^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221120221 is a prime.

It is a super-2 number, since 2×1221120221² = 2982269188270177682, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1221120196 and 1221120205.

It is a congruent 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, 407456 + ... + 410441.

It is an arithmetic number, because the mean of its divisors is an integer number (305484903).

Almost surely, 2^1221120221 is an apocalyptic number.

It is an amenable number.

1221120221 is a deficient number, since it is larger than the sum of its proper divisors (819391).

1221120221 is an equidigital number, since it uses as much as digits as its factorization.

1221120221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 819390.

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 1221120221 is about 34944.5306307010. The cubic root of 1221120221 is about 1068.8566763963.

Adding to 1221120221 its reverse (1220211221), we get a palindrome (2441331442).

The spelling of 1221120221 in words is "one billion, two hundred twenty-one million, one hundred twenty thousand, two hundred twenty-one".