91111661 has 4 divisors (see below), whose sum is σ = 91638492. Its totient is φ = 90584832.

The previous prime is 91111651. The next prime is 91111663. The reversal of 91111661 is 16611119.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 58049161 + 33062500 = 7619^2 + 5750^2 .

It is a cyclic number.

It is not a de Polignac number, because 91111661 - 2⁶ = 91111597 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 91111661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91111663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 263156 + ... + 263501.

It is an arithmetic number, because the mean of its divisors is an integer number (22909623).

Almost surely, 2^91111661 is an apocalyptic number.

It is an amenable number.

91111661 is a deficient number, since it is larger than the sum of its proper divisors (526831).

91111661 is a wasteful number, since it uses less digits than its factorization.

91111661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526830.

The product of its digits is 324, while the sum is 26.

The square root of 91111661 is about 9545.2428465702. The cubic root of 91111661 is about 449.9780417269.

The spelling of 91111661 in words is "ninety-one million, one hundred eleven thousand, six hundred sixty-one".