91811191 has 2 divisors, whose sum is σ = 91811192. Its totient is φ = 91811190.

The previous prime is 91811183. The next prime is 91811201. The reversal of 91811191 is 19111819.

It is a weak prime.

It is an emirp because it is prime and its reverse (19111819) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91811191 - 2³ = 91811183 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91811891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45905595 + 45905596.

It is an arithmetic number, because the mean of its divisors is an integer number (45905596).

Almost surely, 2^91811191 is an apocalyptic number.

91811191 is a deficient number, since it is larger than the sum of its proper divisors (1).

91811191 is an equidigital number, since it uses as much as digits as its factorization.

91811191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 648, while the sum is 31.

The square root of 91811191 is about 9581.8156421422. The cubic root of 91811191 is about 451.1267091038.

The spelling of 91811191 in words is "ninety-one million, eight hundred eleven thousand, one hundred ninety-one".