91971081 has 6 divisors (see below), whose sum is σ = 132847130. Its totient is φ = 61314048.

The previous prime is 91971067. The next prime is 91971107. The reversal of 91971081 is 18017919.

It can be written as a sum of positive squares in only one way, i.e., 90725625 + 1245456 = 9525^2 + 1116^2 .

It is not a de Polignac number, because 91971081 - 2⁵ = 91971049 is a prime.

It is a super-3 number, since 3×91971081³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (91971031) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5109496 + ... + 5109513.

Almost surely, 2^91971081 is an apocalyptic number.

It is an amenable number.

91971081 is a deficient number, since it is larger than the sum of its proper divisors (40876049).

91971081 is a wasteful number, since it uses less digits than its factorization.

91971081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10219015 (or 10219012 counting only the distinct ones).

The product of its (nonzero) digits is 4536, while the sum is 36.

The square root of 91971081 is about 9590.1554210555. The cubic root of 91971081 is about 451.3884376112.

The spelling of 91971081 in words is "ninety-one million, nine hundred seventy-one thousand, eighty-one".