91185561 has 8 divisors (see below), whose sum is σ = 135089760. Its totient is φ = 60790356.

The previous prime is 91185559. The next prime is 91185571. The reversal of 91185561 is 16558119.

91185561 is a `hidden beast` number, since 9 + 11 + 85 + 561 = 666.

It is not a de Polignac number, because 91185561 - 2¹ = 91185559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91185551) 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, 1688595 + ... + 1688648.

It is an arithmetic number, because the mean of its divisors is an integer number (16886220).

Almost surely, 2^91185561 is an apocalyptic number.

It is an amenable number.

91185561 is a deficient number, since it is larger than the sum of its proper divisors (43904199).

91185561 is a wasteful number, since it uses less digits than its factorization.

91185561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3377252 (or 3377246 counting only the distinct ones).

The product of its digits is 10800, while the sum is 36.

The square root of 91185561 is about 9549.1131001785. The cubic root of 91185561 is about 450.0996668129.

The spelling of 91185561 in words is "ninety-one million, one hundred eighty-five thousand, five hundred sixty-one".