91315728 has 80 divisors (see below), whose sum is σ = 299564160. Its totient is φ = 26089344.

The previous prime is 91315723. The next prime is 91315769. The reversal of 91315728 is 82751319.

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 = 91315692 and 91315701.

It is not an unprimeable number, because it can be changed into a prime (91315723) 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, 12075 + ... + 18122.

It is an arithmetic number, because the mean of its divisors is an integer number (3744552).

Almost surely, 2^91315728 is an apocalyptic number.

It is an amenable number.

91315728 is an abundant number, since it is smaller than the sum of its proper divisors (208248432).

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

91315728 is a wasteful number, since it uses less digits than its factorization.

91315728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30221 (or 30209 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 91315728 is about 9555.9263287240. The cubic root of 91315728 is about 450.3137367697.

It can be divided in two parts, 913 and 15728, that added together give a square (16641 = 129²).

The spelling of 91315728 in words is "ninety-one million, three hundred fifteen thousand, seven hundred twenty-eight".