91651891 has 2 divisors, whose sum is σ = 91651892. Its totient is φ = 91651890.

The previous prime is 91651873. The next prime is 91651907. The reversal of 91651891 is 19815619.

It is a strong prime.

It is an emirp because it is prime and its reverse (19815619) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91651891 - 2⁹ = 91651379 is a prime.

It is not a weakly prime, because it can be changed into another prime (91651691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45825945 + 45825946.

It is an arithmetic number, because the mean of its divisors is an integer number (45825946).

Almost surely, 2^91651891 is an apocalyptic number.

91651891 is a deficient number, since it is larger than the sum of its proper divisors (1).

91651891 is an equidigital number, since it uses as much as digits as its factorization.

91651891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440, while the sum is 40.

The square root of 91651891 is about 9573.4994124406. The cubic root of 91651891 is about 450.8656440213.

The spelling of 91651891 in words is "ninety-one million, six hundred fifty-one thousand, eight hundred ninety-one".