8991640 has 64 divisors (see below), whose sum is σ = 24494400. Its totient is φ = 2899968.

The previous prime is 8991637. The next prime is 8991649. The reversal of 8991640 is 461998.

8991640 is nontrivially palindromic in base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 8991640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8991649) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3816 + ... + 5704.

It is an arithmetic number, because the mean of its divisors is an integer number (382725).

Almost surely, 2^8991640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 8991640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12247200).

8991640 is an abundant number, since it is smaller than the sum of its proper divisors (15502760).

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

8991640 is a wasteful number, since it uses less digits than its factorization.

8991640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1924 (or 1920 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 8991640 is about 2998.6063429533. The cubic root of 8991640 is about 207.9439567947.

The spelling of 8991640 in words is "eight million, nine hundred ninety-one thousand, six hundred forty".