91431850128 has 80 divisors (see below), whose sum is σ = 242518436160. Its totient is φ = 29666714112.

The previous prime is 91431850123. The next prime is 91431850229. The reversal of 91431850128 is 82105813419.

It is a Cunningham number, because it is equal to 302377²-1.

It is a super-3 number, since 3×91431850128³ (a number of 34 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 91431850128.

It is not an unprimeable number, because it can be changed into a prime (91431850123) 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, 529158 + ... + 680346.

It is an arithmetic number, because the mean of its divisors is an integer number (3031480452).

Almost surely, 2^91431850128 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 91431850128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121259218080).

91431850128 is an abundant number, since it is smaller than the sum of its proper divisors (151086586032).

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

91431850128 is a wasteful number, since it uses less digits than its factorization.

91431850128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151536 (or 151530 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 42.

The spelling of 91431850128 in words is "ninety-one billion, four hundred thirty-one million, eight hundred fifty thousand, one hundred twenty-eight".