8643981 has 4 divisors (see below), whose sum is σ = 11525312. Its totient is φ = 5762652.

The previous prime is 8643959. The next prime is 8643991. The reversal of 8643981 is 1893468.

8643981 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 8643981 - 2¹⁷ = 8512909 is a prime.

It is a super-2 number, since 2×8643981² = 149436815056722, which contains 22 as substring.

It is a Duffinian number.

8643981 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8643941) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1440661 + ... + 1440666.

It is an arithmetic number, because the mean of its divisors is an integer number (2881328).

Almost surely, 2^8643981 is an apocalyptic number.

It is an amenable number.

8643981 is a deficient number, since it is larger than the sum of its proper divisors (2881331).

8643981 is a wasteful number, since it uses less digits than its factorization.

8643981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2881330.

The product of its digits is 41472, while the sum is 39.

The square root of 8643981 is about 2940.0647952044. The cubic root of 8643981 is about 205.2286245687.

The spelling of 8643981 in words is "eight million, six hundred forty-three thousand, nine hundred eighty-one".