91378681 has 8 divisors (see below), whose sum is σ = 94779720. Its totient is φ = 87994368.

The previous prime is 91378673. The next prime is 91378691. The reversal of 91378681 is 18687319.

It can be written as a sum of positive squares in 4 ways, for example, as 50623225 + 40755456 = 7115^2 + 6384^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 91378681 - 2³ = 91378673 is a prime.

It is a super-2 number, since 2×91378681² = 16700126682599522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91378691) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7545 + ... + 15481.

It is an arithmetic number, because the mean of its divisors is an integer number (11847465).

Almost surely, 2^91378681 is an apocalyptic number.

It is an amenable number.

91378681 is a deficient number, since it is larger than the sum of its proper divisors (3401039).

91378681 is a wasteful number, since it uses less digits than its factorization.

91378681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8363.

The product of its digits is 72576, while the sum is 43.

The square root of 91378681 is about 9559.2196857275. The cubic root of 91378681 is about 450.4171949920.

The spelling of 91378681 in words is "ninety-one million, three hundred seventy-eight thousand, six hundred eighty-one".