91981785 has 16 divisors (see below), whose sum is σ = 168195456. Its totient is φ = 42048768.

The previous prime is 91981777. The next prime is 91981789. The reversal of 91981785 is 58718919.

It is not a de Polignac number, because 91981785 - 2³ = 91981777 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91981789) 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 15 ways as a sum of consecutive naturals, for example, 437904 + ... + 438113.

It is an arithmetic number, because the mean of its divisors is an integer number (10512216).

Almost surely, 2^91981785 is an apocalyptic number.

It is an amenable number.

91981785 is a deficient number, since it is larger than the sum of its proper divisors (76213671).

91981785 is a wasteful number, since it uses less digits than its factorization.

91981785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 876032.

The product of its digits is 181440, while the sum is 48.

The square root of 91981785 is about 9590.7134771090. The cubic root of 91981785 is about 451.4059484575.

The spelling of 91981785 in words is "ninety-one million, nine hundred eighty-one thousand, seven hundred eighty-five".