8991564 has 12 divisors (see below), whose sum is σ = 20980344. Its totient is φ = 2997184.

The previous prime is 8991559. The next prime is 8991599. The reversal of 8991564 is 4651998.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 374637 + ... + 374660.

It is an arithmetic number, because the mean of its divisors is an integer number (1748362).

Almost surely, 2^8991564 is an apocalyptic number.

It is an amenable number.

8991564 is an abundant number, since it is smaller than the sum of its proper divisors (11988780).

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

8991564 is a wasteful number, since it uses less digits than its factorization.

8991564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 749304 (or 749302 counting only the distinct ones).

The product of its digits is 77760, while the sum is 42.

The square root of 8991564 is about 2998.5936703728. The cubic root of 8991564 is about 207.9433709251.

The spelling of 8991564 in words is "eight million, nine hundred ninety-one thousand, five hundred sixty-four".