8911981 has 4 divisors (see below), whose sum is σ = 9597532. Its totient is φ = 8226432.

The previous prime is 8911979. The next prime is 8911997. The reversal of 8911981 is 1891198.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5336100 + 3575881 = 2310^2 + 1891^2 .

It is a cyclic number.

It is not a de Polignac number, because 8911981 - 2¹ = 8911979 is a prime.

It is a super-2 number, since 2×8911981² = 158846810688722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 8911981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8911901) 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, 342756 + ... + 342781.

It is an arithmetic number, because the mean of its divisors is an integer number (2399383).

Almost surely, 2^8911981 is an apocalyptic number.

It is an amenable number.

8911981 is a deficient number, since it is larger than the sum of its proper divisors (685551).

8911981 is a wasteful number, since it uses less digits than its factorization.

8911981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 685550.

The product of its digits is 5184, while the sum is 37.

The square root of 8911981 is about 2985.2941228629. The cubic root of 8911981 is about 207.3280600137.

The spelling of 8911981 in words is "eight million, nine hundred eleven thousand, nine hundred eighty-one".