91691540 has 48 divisors (see below), whose sum is σ = 207267984. Its totient is φ = 33945600.

The previous prime is 91691519. The next prime is 91691543. The reversal of 91691540 is 4519619.

It can be written as a sum of positive squares in 8 ways, for example, as 183184 + 91508356 = 428^2 + 9566^2 .

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 91691540.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91691543) 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, 18530 + ... + 22950.

It is an arithmetic number, because the mean of its divisors is an integer number (4318083).

Almost surely, 2^91691540 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91691540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (103633992).

91691540 is an abundant number, since it is smaller than the sum of its proper divisors (115576444).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

91691540 is a wasteful number, since it uses less digits than its factorization.

91691540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4508 (or 4506 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 35.

The square root of 91691540 is about 9575.5699569268. The cubic root of 91691540 is about 450.9306501168.

The spelling of 91691540 in words is "ninety-one million, six hundred ninety-one thousand, five hundred forty".