91172081 has 16 divisors (see below), whose sum is σ = 122414208. Its totient is φ = 65577600.

The previous prime is 91172077. The next prime is 91172087. The reversal of 91172081 is 18027119.

It is not a de Polignac number, because 91172081 - 2² = 91172077 is a prime.

It is a super-2 number, since 2×91172081² = 16624696707741122, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (91172087) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44540 + ... + 46541.

It is an arithmetic number, because the mean of its divisors is an integer number (7650888).

Almost surely, 2^91172081 is an apocalyptic number.

91172081 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

It is an amenable number.

91172081 is a deficient number, since it is larger than the sum of its proper divisors (31242127).

91172081 is a wasteful number, since it uses less digits than its factorization.

91172081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91112.

The product of its (nonzero) digits is 1008, while the sum is 29.

The square root of 91172081 is about 9548.4072493793. The cubic root of 91172081 is about 450.0774862452.

The spelling of 91172081 in words is "ninety-one million, one hundred seventy-two thousand, eighty-one".