280561865 has 4 divisors (see below), whose sum is σ = 336674244. Its totient is φ = 224449488.

The previous prime is 280561859. The next prime is 280561867. The reversal of 280561865 is 568165082.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 568165082 = 2 ⋅284082541.

It can be written as a sum of positive squares in 2 ways, for example, as 106110601 + 174451264 = 10301^2 + 13208^2 .

It is a cyclic number.

It is not a de Polignac number, because 280561865 - 2⁸ = 280561609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (280561867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28056182 + ... + 28056191.

It is an arithmetic number, because the mean of its divisors is an integer number (84168561).

Almost surely, 2^280561865 is an apocalyptic number.

It is an amenable number.

280561865 is a deficient number, since it is larger than the sum of its proper divisors (56112379).

280561865 is an equidigital number, since it uses as much as digits as its factorization.

280561865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56112378.

The product of its (nonzero) digits is 115200, while the sum is 41.

The square root of 280561865 is about 16749.9810447654. The cubic root of 280561865 is about 654.6505643461.

The spelling of 280561865 in words is "two hundred eighty million, five hundred sixty-one thousand, eight hundred sixty-five".