91990643 has 4 divisors (see below), whose sum is σ = 93099048. Its totient is φ = 90882240.

The previous prime is 91990637. The next prime is 91990649. The reversal of 91990643 is 34609919.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 34609919 = 31 ⋅1116449.

It is an interprime number because it is at equal distance from previous prime (91990637) and next prime (91990649).

It is a cyclic number.

It is not a de Polignac number, because 91990643 - 2⁴ = 91990627 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 91990643.

It is not an unprimeable number, because it can be changed into a prime (91990649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 554078 + ... + 554243.

It is an arithmetic number, because the mean of its divisors is an integer number (23274762).

Almost surely, 2^91990643 is an apocalyptic number.

91990643 is a deficient number, since it is larger than the sum of its proper divisors (1108405).

91990643 is a wasteful number, since it uses less digits than its factorization.

91990643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1108404.

The product of its (nonzero) digits is 52488, while the sum is 41.

The square root of 91990643 is about 9591.1752668794. The cubic root of 91990643 is about 451.4204383754.

The spelling of 91990643 in words is "ninety-one million, nine hundred ninety thousand, six hundred forty-three".