91981507761 has 24 divisors (see below), whose sum is σ = 156089833536. Its totient is φ = 51458185440.

The previous prime is 91981507721. The next prime is 91981507763. The reversal of 91981507761 is 16770518919.

It is not a de Polignac number, because 91981507761 - 2¹⁴ = 91981491377 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 91981507698 and 91981507707.

It is not an unprimeable number, because it can be changed into a prime (91981507763) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 35733565 + ... + 35736138.

It is an arithmetic number, because the mean of its divisors is an integer number (6503743064).

Almost surely, 2^91981507761 is an apocalyptic number.

It is an amenable number.

91981507761 is a deficient number, since it is larger than the sum of its proper divisors (64108325775).

91981507761 is a wasteful number, since it uses less digits than its factorization.

91981507761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71469733 (or 71469730 counting only the distinct ones).

The product of its (nonzero) digits is 952560, while the sum is 54.

The spelling of 91981507761 in words is "ninety-one billion, nine hundred eighty-one million, five hundred seven thousand, seven hundred sixty-one".