2911981 has 4 divisors (see below), whose sum is σ = 3083292. Its totient is φ = 2740672.

The previous prime is 2911973. The next prime is 2912009. The reversal of 2911981 is 1891192.

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 855625 + 2056356 = 925^2 + 1434^2 .

It is not a de Polignac number, because 2911981 - 2³ = 2911973 is a prime.

It is a super-2 number, since 2×2911981² = 16959266688722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2911901) 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, 85630 + ... + 85663.

It is an arithmetic number, because the mean of its divisors is an integer number (770823).

2^2911981 is an apocalyptic number.

It is an amenable number.

2911981 is a deficient number, since it is larger than the sum of its proper divisors (171311).

2911981 is a wasteful number, since it uses less digits than its factorization.

2911981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171310.

The product of its digits is 1296, while the sum is 31.

The square root of 2911981 is about 1706.4527535212. The cubic root of 2911981 is about 142.8004290592.

The spelling of 2911981 in words is "two million, nine hundred eleven thousand, nine hundred eighty-one".