8999991 has 96 divisors (see below), whose sum is σ = 18590208. Its totient is φ = 4199040.

The previous prime is 8999981. The next prime is 8999993. The reversal of 8999991 is 1999998.

It is not a de Polignac number, because 8999991 - 2⁶ = 8999927 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8999993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 243225 + ... + 243261.

It is an arithmetic number, because the mean of its divisors is an integer number (193648).

Almost surely, 2^8999991 is an apocalyptic number.

8999991 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

8999991 is an abundant number, since it is smaller than the sum of its proper divisors (9590217).

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

8999991 is a wasteful number, since it uses less digits than its factorization.

8999991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83 (or 71 counting only the distinct ones).

The product of its digits is 472392, while the sum is 54.

The square root of 8999991 is about 2999.9984999996. The cubic root of 8999991 is about 208.0083129690.

It can be divided in two parts, 8 and 999991, that added together give a palindrome (999999).

The spelling of 8999991 in words is "eight million, nine hundred ninety-nine thousand, nine hundred ninety-one".