1221210091909 has 2 divisors, whose sum is σ = 1221210091910. Its totient is φ = 1221210091908.

The previous prime is 1221210091879. The next prime is 1221210091967. The reversal of 1221210091909 is 9091900121221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1053476432100 + 167733659809 = 1026390^2 + 409553^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221210091909 - 2¹¹ = 1221210089861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221210091979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610605045954 + 610605045955.

It is an arithmetic number, because the mean of its divisors is an integer number (610605045955).

Almost surely, 2^{1221210091909} is an apocalyptic number.

It is an amenable number.

1221210091909 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221210091909 is an equidigital number, since it uses as much as digits as its factorization.

1221210091909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 37.

The spelling of 1221210091909 in words is "one trillion, two hundred twenty-one billion, two hundred ten million, ninety-one thousand, nine hundred nine".