91388814561 has 24 divisors (see below), whose sum is σ = 147070594944. Its totient is φ = 54208707360.

The previous prime is 91388814553. The next prime is 91388814563. The reversal of 91388814561 is 16541888319.

It is a happy number.

91388814561 is a `hidden beast` number, since 91 + 388 + 81 + 45 + 61 = 666.

It is not a de Polignac number, because 91388814561 - 2³ = 91388814553 is a prime.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 91388814498 and 91388814507.

It is not an unprimeable number, because it can be changed into a prime (91388814563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9815766 + ... + 9825071.

It is an arithmetic number, because the mean of its divisors is an integer number (6127941456).

Almost surely, 2^91388814561 is an apocalyptic number.

It is an amenable number.

91388814561 is a deficient number, since it is larger than the sum of its proper divisors (55681780383).

91388814561 is a wasteful number, since it uses less digits than its factorization.

91388814561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19640901 (or 19640898 counting only the distinct ones).

The product of its digits is 1658880, while the sum is 54.

The spelling of 91388814561 in words is "ninety-one billion, three hundred eighty-eight million, eight hundred fourteen thousand, five hundred sixty-one".