91609128 has 96 divisors (see below), whose sum is σ = 270215400. Its totient is φ = 27869184.

The previous prime is 91609117. The next prime is 91609171. The reversal of 91609128 is 82190619.

It can be written as a sum of positive squares in 4 ways, for example, as 52446564 + 39162564 = 7242^2 + 6258^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 91609092 and 91609101.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 90288 + ... + 91296.

Almost surely, 2^91609128 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 91609128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (135107700).

91609128 is an abundant number, since it is smaller than the sum of its proper divisors (178606272).

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

91609128 is a wasteful number, since it uses less digits than its factorization.

91609128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1131 (or 1124 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 91609128 is about 9571.2657470159. The cubic root of 91609128 is about 450.7955113824.

The spelling of 91609128 in words is "ninety-one million, six hundred nine thousand, one hundred twenty-eight".