91001220197 has 2 divisors, whose sum is σ = 91001220198. Its totient is φ = 91001220196.

The previous prime is 91001220139. The next prime is 91001220287. The reversal of 91001220197 is 79102210019.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 88138328161 + 2862892036 = 296881^2 + 53506^2 .

It is a cyclic number.

It is not a de Polignac number, because 91001220197 - 2³² = 86706252901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91001220397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45500610098 + 45500610099.

It is an arithmetic number, because the mean of its divisors is an integer number (45500610099).

Almost surely, 2^91001220197 is an apocalyptic number.

It is an amenable number.

91001220197 is a deficient number, since it is larger than the sum of its proper divisors (1).

91001220197 is an equidigital number, since it uses as much as digits as its factorization.

91001220197 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2268, while the sum is 32.

The spelling of 91001220197 in words is "ninety-one billion, one million, two hundred twenty thousand, one hundred ninety-seven".