8640981 has 12 divisors (see below), whose sum is σ = 13215852. Its totient is φ = 5421696.

The previous prime is 8640977. The next prime is 8641007. The reversal of 8640981 is 1890468.

It is a happy number.

8640981 is a `hidden beast` number, since 8 + 640 + 9 + 8 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 2924100 + 5716881 = 1710^2 + 2391^2 .

It is not a de Polignac number, because 8640981 - 2² = 8640977 is a prime.

It is a super-2 number, since 2×8640981² = 149333105284722, which contains 22 as substring.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8640911) 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 11 ways as a sum of consecutive naturals, for example, 28086 + ... + 28391.

It is an arithmetic number, because the mean of its divisors is an integer number (1101321).

Almost surely, 2^8640981 is an apocalyptic number.

It is an amenable number.

8640981 is a deficient number, since it is larger than the sum of its proper divisors (4574871).

8640981 is a wasteful number, since it uses less digits than its factorization.

8640981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56500 (or 56497 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 8640981 is about 2939.5545580921. The cubic root of 8640981 is about 205.2048794481.

The spelling of 8640981 in words is "eight million, six hundred forty thousand, nine hundred eighty-one".