81986091 has 24 divisors (see below), whose sum is σ = 121985472. Its totient is φ = 48932400.

The previous prime is 81986077. The next prime is 81986141. The reversal of 81986091 is 19068918.

It is not a de Polignac number, because 81986091 - 2⁵ = 81986059 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81986011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22636 + ... + 26006.

It is an arithmetic number, because the mean of its divisors is an integer number (5082728).

Almost surely, 2^81986091 is an apocalyptic number.

81986091 is a deficient number, since it is larger than the sum of its proper divisors (39999381).

81986091 is a wasteful number, since it uses less digits than its factorization.

81986091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3463 (or 3452 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 42.

The square root of 81986091 is about 9054.6171095193. The cubic root of 81986091 is about 434.4235832070.

The spelling of 81986091 in words is "eighty-one million, nine hundred eighty-six thousand, ninety-one".