1221011001209 has 4 divisors (see below), whose sum is σ = 1221468140160. Its totient is φ = 1220553862260.

The previous prime is 1221011001187. The next prime is 1221011001211. The reversal of 1221011001209 is 9021001101221.

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 1221011001209 - 2²⁸ = 1220742565753 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 (1221011001409) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 228565469 + ... + 228570810.

It is an arithmetic number, because the mean of its divisors is an integer number (305367035040).

Almost surely, 2^{1221011001209} is an apocalyptic number.

It is an amenable number.

1221011001209 is a deficient number, since it is larger than the sum of its proper divisors (457138951).

1221011001209 is an equidigital number, since it uses as much as digits as its factorization.

1221011001209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 457138950.

The product of its (nonzero) digits is 72, while the sum is 20.

The spelling of 1221011001209 in words is "one trillion, two hundred twenty-one billion, eleven million, one thousand, two hundred nine".