1221000100091 has 2 divisors, whose sum is σ = 1221000100092. Its totient is φ = 1221000100090.

The previous prime is 1221000100043. The next prime is 1221000100121. The reversal of 1221000100091 is 1900010001221.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1221000100091 - 2³⁰ = 1219926358267 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221000100391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610500050045 + 610500050046.

It is an arithmetic number, because the mean of its divisors is an integer number (610500050046).

Almost surely, 2^{1221000100091} is an apocalyptic number.

1221000100091 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221000100091 is an equidigital number, since it uses as much as digits as its factorization.

1221000100091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36, while the sum is 17.

The spelling of 1221000100091 in words is "one trillion, two hundred twenty-one billion, one hundred thousand, ninety-one".