91169777978 has 8 divisors (see below), whose sum is σ = 136875799380. Its totient is φ = 45544511520.

The previous prime is 91169777971. The next prime is 91169777981. The reversal of 91169777978 is 87977796119.

It can be written as a sum of positive squares in 2 ways, for example, as 89414754529 + 1755023449 = 299023^2 + 41893^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (91169777971) 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 3 ways as a sum of consecutive naturals, for example, 20185913 + ... + 20190428.

Almost surely, 2^91169777978 is an apocalyptic number.

91169777978 is a deficient number, since it is larger than the sum of its proper divisors (45706021402).

91169777978 is a wasteful number, since it uses less digits than its factorization.

91169777978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40377472.

The product of its digits is 84015792, while the sum is 71.

The spelling of 91169777978 in words is "ninety-one billion, one hundred sixty-nine million, seven hundred seventy-seven thousand, nine hundred seventy-eight".