2781281 has 8 divisors (see below), whose sum is σ = 2868264. Its totient is φ = 2695680.

The previous prime is 2781271. The next prime is 2781293. The reversal of 2781281 is 1821872.

2781281 = 119² + 120² + ... + 215².

It can be written as a sum of positive squares in 4 ways, for example, as 483025 + 2298256 = 695^2 + 1516^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2781281 - 2¹⁸ = 2519137 is a prime.

It is a super-2 number, since 2×2781281² = 15471048001922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2781211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4871 + ... + 5411.

It is an arithmetic number, because the mean of its divisors is an integer number (358533).

2^2781281 is an apocalyptic number.

It is an amenable number.

2781281 is a deficient number, since it is larger than the sum of its proper divisors (86983).

2781281 is an equidigital number, since it uses as much as digits as its factorization.

2781281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 691.

The product of its digits is 1792, while the sum is 29.

The square root of 2781281 is about 1667.7173021828. The cubic root of 2781281 is about 140.6311806995.

The spelling of 2781281 in words is "two million, seven hundred eighty-one thousand, two hundred eighty-one".