91666661 has 8 divisors (see below), whose sum is σ = 96142464. Its totient is φ = 87231760.

The previous prime is 91666633. The next prime is 91666667. The reversal of 91666661 is 16666619.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 91666661 - 2¹⁸ = 91404517 is a prime.

It is a fibodiv number, since the Fibonacci-like sequence with seeds 9 and 1666661 contains 91666661 itself.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91666667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5585 + ... + 14646.

It is an arithmetic number, because the mean of its divisors is an integer number (12017808).

Almost surely, 2^91666661 is an apocalyptic number.

It is an amenable number.

91666661 is a deficient number, since it is larger than the sum of its proper divisors (4475803).

91666661 is a wasteful number, since it uses less digits than its factorization.

91666661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20451.

The product of its digits is 69984, while the sum is 41.

The square root of 91666661 is about 9574.2707816314. The cubic root of 91666661 is about 450.8898622081.

The spelling of 91666661 in words is "ninety-one million, six hundred sixty-six thousand, six hundred sixty-one".