91109201021 has 2 divisors, whose sum is σ = 91109201022. Its totient is φ = 91109201020.

The previous prime is 91109201009. The next prime is 91109201059. The reversal of 91109201021 is 12010290119.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 84163812100 + 6945388921 = 290110^2 + 83339^2 .

It is a cyclic number.

It is not a de Polignac number, because 91109201021 - 2³⁴ = 73929331837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91109203021) 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, 45554600510 + 45554600511.

It is an arithmetic number, because the mean of its divisors is an integer number (45554600511).

Almost surely, 2^91109201021 is an apocalyptic number.

It is an amenable number.

91109201021 is a deficient number, since it is larger than the sum of its proper divisors (1).

91109201021 is an equidigital number, since it uses as much as digits as its factorization.

91109201021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 26.

The spelling of 91109201021 in words is "ninety-one billion, one hundred nine million, two hundred one thousand, twenty-one".