91777728 has 112 divisors (see below), whose sum is σ = 289681920. Its totient is φ = 25073664.

The previous prime is 91777727. The next prime is 91777729. The reversal of 91777728 is 82777719.

It is an interprime number because it is at equal distance from previous prime (91777727) and next prime (91777729).

It is a tau number, because it is divible by the number of its divisors (112).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is not an unprimeable number, because it can be changed into a prime (91777727) 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, 29428 + ... + 32396.

Almost surely, 2^91777728 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 91777728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (144840960).

91777728 is an abundant number, since it is smaller than the sum of its proper divisors (197904192).

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

91777728 is a wasteful number, since it uses less digits than its factorization.

91777728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3014 (or 3004 counting only the distinct ones).

The product of its digits is 345744, while the sum is 48.

The square root of 91777728 is about 9580.0693108140. The cubic root of 91777728 is about 451.0718941177.

Subtracting from 91777728 its reverse (82777719), we obtain a palindrome (9000009).

The spelling of 91777728 in words is "ninety-one million, seven hundred seventy-seven thousand, seven hundred twenty-eight".