1001221221191 has 2 divisors, whose sum is σ = 1001221221192. Its totient is φ = 1001221221190.

The previous prime is 1001221221179. The next prime is 1001221221251. The reversal of 1001221221191 is 1911221221001.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1001221221191 - 2²⁶ = 1001154112327 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1001221224191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 500610610595 + 500610610596.

It is an arithmetic number, because the mean of its divisors is an integer number (500610610596).

Almost surely, 2^{1001221221191} is an apocalyptic number.

1001221221191 is a deficient number, since it is larger than the sum of its proper divisors (1).

1001221221191 is an equidigital number, since it uses as much as digits as its factorization.

1001221221191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 23.

Adding to 1001221221191 its reverse (1911221221001), we get a palindrome (2912442442192).

The spelling of 1001221221191 in words is "one trillion, one billion, two hundred twenty-one million, two hundred twenty-one thousand, one hundred ninety-one".