91863720191 has 2 divisors, whose sum is σ = 91863720192. Its totient is φ = 91863720190.

The previous prime is 91863720161. The next prime is 91863720197. The reversal of 91863720191 is 19102736819.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 91863720191 - 2⁶ = 91863720127 is a prime.

It is a super-3 number, since 3×91863720191³ (a number of 34 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91863720197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45931860095 + 45931860096.

It is an arithmetic number, because the mean of its divisors is an integer number (45931860096).

Almost surely, 2^91863720191 is an apocalyptic number.

91863720191 is a deficient number, since it is larger than the sum of its proper divisors (1).

91863720191 is an equidigital number, since it uses as much as digits as its factorization.

91863720191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 163296, while the sum is 47.

The spelling of 91863720191 in words is "ninety-one billion, eight hundred sixty-three million, seven hundred twenty thousand, one hundred ninety-one".