991168893818 has 4 divisors (see below), whose sum is σ = 1486753340730. Its totient is φ = 495584446908.

The previous prime is 991168893791. The next prime is 991168893881. The reversal of 991168893818 is 818398861199.

991168893818 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 564411120529 + 426757773289 = 751273^2 + 653267^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 247792223453 + ... + 247792223456.

Almost surely, 2^991168893818 is an apocalyptic number.

991168893818 is a deficient number, since it is larger than the sum of its proper divisors (495584446912).

991168893818 is a wasteful number, since it uses less digits than its factorization.

991168893818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 495584446911.

The product of its digits is 53747712, while the sum is 71.

The spelling of 991168893818 in words is "nine hundred ninety-one billion, one hundred sixty-eight million, eight hundred ninety-three thousand, eight hundred eighteen".