91661798 has 4 divisors (see below), whose sum is σ = 137492700. Its totient is φ = 45830898.

The previous prime is 91661777. The next prime is 91661813. The reversal of 91661798 is 89716619.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 89716619 = 43 ⋅2086433.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 22915448 + ... + 22915451.

It is an arithmetic number, because the mean of its divisors is an integer number (34373175).

Almost surely, 2^91661798 is an apocalyptic number.

91661798 is a deficient number, since it is larger than the sum of its proper divisors (45830902).

91661798 is a wasteful number, since it uses less digits than its factorization.

91661798 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45830901.

The product of its digits is 163296, while the sum is 47.

The square root of 91661798 is about 9574.0168163629. The cubic root of 91661798 is about 450.8818886943.

The spelling of 91661798 in words is "ninety-one million, six hundred sixty-one thousand, seven hundred ninety-eight".