91638571 has 2 divisors, whose sum is σ = 91638572. Its totient is φ = 91638570.

The previous prime is 91638559. The next prime is 91638587. The reversal of 91638571 is 17583619.

It is a weak prime.

It is an emirp because it is prime and its reverse (17583619) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91638571 is a prime.

It is not a weakly prime, because it can be changed into another prime (91638541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45819285 + 45819286.

It is an arithmetic number, because the mean of its divisors is an integer number (45819286).

Almost surely, 2^91638571 is an apocalyptic number.

91638571 is a deficient number, since it is larger than the sum of its proper divisors (1).

91638571 is an equidigital number, since it uses as much as digits as its factorization.

91638571 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 45360, while the sum is 40.

The square root of 91638571 is about 9572.8037167802. The cubic root of 91638571 is about 450.8438011501.

The spelling of 91638571 in words is "ninety-one million, six hundred thirty-eight thousand, five hundred seventy-one".