91000728 has 384 divisors, whose sum is σ = 345945600. Its totient is φ = 20901888.

The previous prime is 91000727. The next prime is 91000729. The reversal of 91000728 is 82700019.

It is an interprime number because it is at equal distance from previous prime (91000727) and next prime (91000729).

It is a super-2 number, since 2×91000728² = 16562264993059968, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91000727) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2116275 + ... + 2116317.

It is an arithmetic number, because the mean of its divisors is an integer number (900900).

Almost surely, 2^91000728 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 91000728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (172972800).

91000728 is an abundant number, since it is smaller than the sum of its proper divisors (254944872).

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

91000728 is a wasteful number, since it uses less digits than its factorization.

91000728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111 (or 104 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 91000728 is about 9539.4301716612. The cubic root of 91000728 is about 449.7953439754.

The spelling of 91000728 in words is "ninety-one million, seven hundred twenty-eight", and thus it is an aban number.