91680561 has 36 divisors (see below), whose sum is σ = 155692992. Its totient is φ = 50925024.

The previous prime is 91680559. The next prime is 91680569. The reversal of 91680561 is 16508619.

91680561 is a `hidden beast` number, since 9 + 16 + 80 + 561 = 666.

It is not a de Polignac number, because 91680561 - 2¹ = 91680559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91680569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 85716 + ... + 86778.

Almost surely, 2^91680561 is an apocalyptic number.

It is an amenable number.

91680561 is a deficient number, since it is larger than the sum of its proper divisors (64012431).

91680561 is a wasteful number, since it uses less digits than its factorization.

91680561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1150 (or 1110 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 91680561 is about 9574.9966579629. The cubic root of 91680561 is about 450.9126514907.

The spelling of 91680561 in words is "ninety-one million, six hundred eighty thousand, five hundred sixty-one".