91981318 has 32 divisors (see below), whose sum is σ = 170634240. Its totient is φ = 36560160.

The previous prime is 91981313. The next prime is 91981319. The reversal of 91981318 is 81318919.

It is a happy number.

It is a super-2 number, since 2×91981318² = 16921125722034248, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91981313) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3030 + ... + 13897.

It is an arithmetic number, because the mean of its divisors is an integer number (5332320).

Almost surely, 2^91981318 is an apocalyptic number.

91981318 is a deficient number, since it is larger than the sum of its proper divisors (78652922).

91981318 is a wasteful number, since it uses less digits than its factorization.

91981318 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16972.

The product of its digits is 15552, while the sum is 40.

The square root of 91981318 is about 9590.6891306100. The cubic root of 91981318 is about 451.4051845130.

The spelling of 91981318 in words is "ninety-one million, nine hundred eighty-one thousand, three hundred eighteen".