1221000020209 has 2 divisors, whose sum is σ = 1221000020210. Its totient is φ = 1221000020208.

The previous prime is 1221000020189. The next prime is 1221000020263. The reversal of 1221000020209 is 9020200001221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1172395203984 + 48604816225 = 1082772^2 + 220465^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221000020209 - 2³³ = 1212410085617 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221000020909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610500010104 + 610500010105.

It is an arithmetic number, because the mean of its divisors is an integer number (610500010105).

Almost surely, 2^{1221000020209} is an apocalyptic number.

It is an amenable number.

1221000020209 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221000020209 is an equidigital number, since it uses as much as digits as its factorization.

1221000020209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 19.

The spelling of 1221000020209 in words is "one trillion, two hundred twenty-one billion, twenty thousand, two hundred nine".