1221001211191 has 2 divisors, whose sum is σ = 1221001211192. Its totient is φ = 1221001211190.

The previous prime is 1221001211081. The next prime is 1221001211231. The reversal of 1221001211191 is 1911121001221.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1221001211191 - 2⁹ = 1221001210679 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221001218191) 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 as a sum of consecutive naturals, namely, 610500605595 + 610500605596.

It is an arithmetic number, because the mean of its divisors is an integer number (610500605596).

Almost surely, 2^{1221001211191} is an apocalyptic number.

1221001211191 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221001211191 is an equidigital number, since it uses as much as digits as its factorization.

1221001211191 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 22.

The spelling of 1221001211191 in words is "one trillion, two hundred twenty-one billion, one million, two hundred eleven thousand, one hundred ninety-one".