1221211209 has 8 divisors (see below), whose sum is σ = 1628447680. Its totient is φ = 814057776.

The previous prime is 1221211181. The next prime is 1221211231. The reversal of 1221211209 is 9021121221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1221211209 - 2⁵ = 1221211177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221211709) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34812 + ... + 60450.

It is an arithmetic number, because the mean of its divisors is an integer number (203555960).

Almost surely, 2^1221211209 is an apocalyptic number.

It is an amenable number.

1221211209 is a deficient number, since it is larger than the sum of its proper divisors (407236471).

1221211209 is a wasteful number, since it uses less digits than its factorization.

1221211209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41519.

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 1221211209 is about 34945.8324983109. The cubic root of 1221211209 is about 1068.8832232544.

The spelling of 1221211209 in words is "one billion, two hundred twenty-one million, two hundred eleven thousand, two hundred nine".