1221002221 has 4 divisors (see below), whose sum is σ = 1221169500. Its totient is φ = 1220834944.

The previous prime is 1221002213. The next prime is 1221002261. The reversal of 1221002221 is 1222001221.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1222001221 = 7 ⋅174571603.

It can be written as a sum of positive squares in 2 ways, for example, as 631969321 + 589032900 = 25139^2 + 24270^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221002221 - 2³ = 1221002213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221002201) 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, 72166 + ... + 87463.

It is an arithmetic number, because the mean of its divisors is an integer number (305292375).

Almost surely, 2^1221002221 is an apocalyptic number.

It is an amenable number.

1221002221 is a deficient number, since it is larger than the sum of its proper divisors (167279).

1221002221 is an equidigital number, since it uses as much as digits as its factorization.

1221002221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167278.

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 1221002221 is about 34942.8421997982. The cubic root of 1221002221 is about 1068.8222464937.

Adding to 1221002221 its reverse (1222001221), we get a palindrome (2443003442).

The spelling of 1221002221 in words is "one billion, two hundred twenty-one million, two thousand, two hundred twenty-one".