91381666 has 4 divisors (see below), whose sum is σ = 137072502. Its totient is φ = 45690832.

The previous prime is 91381637. The next prime is 91381673. The reversal of 91381666 is 66618319.

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

It can be written as a sum of positive squares in only one way, i.e., 52056225 + 39325441 = 7215^2 + 6271^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 22845415 + ... + 22845418.

Almost surely, 2^91381666 is an apocalyptic number.

91381666 is a deficient number, since it is larger than the sum of its proper divisors (45690836).

91381666 is a wasteful number, since it uses less digits than its factorization.

91381666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45690835.

The product of its digits is 46656, while the sum is 40.

The square root of 91381666 is about 9559.3758164432. The cubic root of 91381666 is about 450.4220994207.

The spelling of 91381666 in words is "ninety-one million, three hundred eighty-one thousand, six hundred sixty-six".