91665799 has 4 divisors (see below), whose sum is σ = 92214864. Its totient is φ = 91116736.

The previous prime is 91665797. The next prime is 91665803. The reversal of 91665799 is 99756619.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99756619 = 7127 ⋅13997.

It is a cyclic number.

It is not a de Polignac number, because 91665799 - 2¹ = 91665797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91665797) 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, 274282 + ... + 274615.

It is an arithmetic number, because the mean of its divisors is an integer number (23053716).

Almost surely, 2^91665799 is an apocalyptic number.

91665799 is a deficient number, since it is larger than the sum of its proper divisors (549065).

91665799 is a wasteful number, since it uses less digits than its factorization.

91665799 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 549064.

The product of its digits is 918540, while the sum is 52.

The square root of 91665799 is about 9574.2257650423. The cubic root of 91665799 is about 450.8884488689. Note that the first 3 decimals are identical.

The spelling of 91665799 in words is "ninety-one million, six hundred sixty-five thousand, seven hundred ninety-nine".