91172781056 has 352 divisors, whose sum is σ = 236851983360. Its totient is φ = 34136653824.

The previous prime is 91172781041. The next prime is 91172781079. The reversal of 91172781056 is 65018727119.

It is a self number, because there is not a number n which added to its sum of digits gives 91172781056.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 122708621 + ... + 122709363.

Almost surely, 2^91172781056 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 91172781056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118425991680).

91172781056 is an abundant number, since it is smaller than the sum of its proper divisors (145679202304).

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

91172781056 is a wasteful number, since it uses less digits than its factorization.

91172781056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 859 (or 841 counting only the distinct ones).

The product of its (nonzero) digits is 211680, while the sum is 47.

The spelling of 91172781056 in words is "ninety-one billion, one hundred seventy-two million, seven hundred eighty-one thousand, fifty-six".