1221102209 has 4 divisors (see below), whose sum is σ = 1241120340. Its totient is φ = 1201084080.

The previous prime is 1221102193. The next prime is 1221102229. The reversal of 1221102209 is 9022011221.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 397125184 + 823977025 = 19928^2 + 28705^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221102209 - 2⁴ = 1221102193 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1221102229) 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, 10008974 + ... + 10009095.

It is an arithmetic number, because the mean of its divisors is an integer number (310280085).

Almost surely, 2^1221102209 is an apocalyptic number.

It is an amenable number.

1221102209 is a deficient number, since it is larger than the sum of its proper divisors (20018131).

1221102209 is an equidigital number, since it uses as much as digits as its factorization.

1221102209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20018130.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 1221102209 is about 34944.2729070158. The cubic root of 1221102209 is about 1068.8514210193.

The spelling of 1221102209 in words is "one billion, two hundred twenty-one million, one hundred two thousand, two hundred nine".