2817981 has 6 divisors (see below), whose sum is σ = 4070430. Its totient is φ = 1878648.

The previous prime is 2817973. The next prime is 2818027. The reversal of 2817981 is 1897182.

It can be written as a sum of positive squares in only one way, i.e., 2722500 + 95481 = 1650^2 + 309^2 .

It is not a de Polignac number, because 2817981 - 2³ = 2817973 is a prime.

It is a super-2 number, since 2×2817981² = 15882033832722, which contains 22 as substring.

It is a Curzon number.

2817981 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2817181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 156546 + ... + 156563.

It is an arithmetic number, because the mean of its divisors is an integer number (678405).

2^2817981 is an apocalyptic number.

It is an amenable number.

2817981 is a deficient number, since it is larger than the sum of its proper divisors (1252449).

2817981 is a wasteful number, since it uses less digits than its factorization.

2817981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 313115 (or 313112 counting only the distinct ones).

The product of its digits is 8064, while the sum is 36.

The square root of 2817981 is about 1678.6843062351. The cubic root of 2817981 is about 141.2470393824.

The spelling of 2817981 in words is "two million, eight hundred seventeen thousand, nine hundred eighty-one".