1221011209 has 4 divisors (see below), whose sum is σ = 1332012240. Its totient is φ = 1110010180.

The previous prime is 1221011177. The next prime is 1221011221. The reversal of 1221011209 is 9021101221.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1221011209 - 2⁵ = 1221011177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221011249) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55500499 + ... + 55500520.

It is an arithmetic number, because the mean of its divisors is an integer number (333003060).

Almost surely, 2^1221011209 is an apocalyptic number.

It is an amenable number.

1221011209 is a deficient number, since it is larger than the sum of its proper divisors (111001031).

1221011209 is a wasteful number, since it uses less digits than its factorization.

1221011209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111001030.

The product of its (nonzero) digits is 72, while the sum is 19.

The square root of 1221011209 is about 34942.9708095920. The cubic root of 1221011209 is about 1068.8248690799.

The spelling of 1221011209 in words is "one billion, two hundred twenty-one million, eleven thousand, two hundred nine".