9918581 has 4 divisors (see below), whose sum is σ = 9924972. Its totient is φ = 9912192.

The previous prime is 9918563. The next prime is 9918593. The reversal of 9918581 is 1858199.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 5958481 + 3960100 = 2441^2 + 1990^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9918581 is a prime.

It is a super-2 number, since 2×9918581² = 196756498107122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9918521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 791 + ... + 4523.

It is an arithmetic number, because the mean of its divisors is an integer number (2481243).

Almost surely, 2^9918581 is an apocalyptic number.

It is an amenable number.

9918581 is a deficient number, since it is larger than the sum of its proper divisors (6391).

9918581 is a wasteful number, since it uses less digits than its factorization.

9918581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6390.

The product of its digits is 25920, while the sum is 41.

The square root of 9918581 is about 3149.3778750731. The cubic root of 9918581 is about 214.8571685190.

The spelling of 9918581 in words is "nine million, nine hundred eighteen thousand, five hundred eighty-one".