91911212100221 has 2 divisors, whose sum is σ = 91911212100222. Its totient is φ = 91911212100220.

The previous prime is 91911212100193. The next prime is 91911212100241. The reversal of 91911212100221 is 12200121211919.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 91171732495321 + 739479604900 = 9548389^2 + 859930^2 .

It is an emirp because it is prime and its reverse (12200121211919) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91911212100221 is a prime.

It is a super-2 number, since 2×91911212100221² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91911212100241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45955606050110 + 45955606050111.

It is an arithmetic number, because the mean of its divisors is an integer number (45955606050111).

Almost surely, 2^{91911212100221} is an apocalyptic number.

It is an amenable number.

91911212100221 is a deficient number, since it is larger than the sum of its proper divisors (1).

91911212100221 is an equidigital number, since it uses as much as digits as its factorization.

91911212100221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 32.

The spelling of 91911212100221 in words is "ninety-one trillion, nine hundred eleven billion, two hundred twelve million, one hundred thousand, two hundred twenty-one".