91991671 has 2 divisors, whose sum is σ = 91991672. Its totient is φ = 91991670.

The previous prime is 91991591. The next prime is 91991681. The reversal of 91991671 is 17619919.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (17619919) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91991671 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91991681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45995835 + 45995836.

It is an arithmetic number, because the mean of its divisors is an integer number (45995836).

Almost surely, 2^91991671 is an apocalyptic number.

91991671 is a deficient number, since it is larger than the sum of its proper divisors (1).

91991671 is an equidigital number, since it uses as much as digits as its factorization.

91991671 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30618, while the sum is 43.

The square root of 91991671 is about 9591.2288576595. The cubic root of 91991671 is about 451.4221199178.

The spelling of 91991671 in words is "ninety-one million, nine hundred ninety-one thousand, six hundred seventy-one".