91389288978 has 48 divisors (see below), whose sum is σ = 214474380120. Its totient is φ = 27957226752.

The previous prime is 91389288923. The next prime is 91389288983. The reversal of 91389288978 is 87988298319.

It can be written as a sum of positive squares in 4 ways, for example, as 64066190769 + 27323098209 = 253113^2 + 165297^2 .

It is a Curzon number.

It is an unprimeable number.

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, 1088283 + ... + 1169246.

Almost surely, 2^91389288978 is an apocalyptic number.

91389288978 is an abundant number, since it is smaller than the sum of its proper divisors (123085091142).

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

91389288978 is a wasteful number, since it uses less digits than its factorization.

91389288978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2257723 (or 2257720 counting only the distinct ones).

The product of its digits is 125411328, while the sum is 72.

The spelling of 91389288978 in words is "ninety-one billion, three hundred eighty-nine million, two hundred eighty-eight thousand, nine hundred seventy-eight".