280561 has 2 divisors, whose sum is σ = 280562. Its totient is φ = 280560.

The previous prime is 280549. The next prime is 280583. The reversal of 280561 is 165082.

It is a happy number.

It is an a-pointer prime, because the next prime (280583) can be obtained adding 280561 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 144400 + 136161 = 380^2 + 369^2 .

It is a cyclic number.

It is not a de Polignac number, because 280561 - 2¹³ = 272369 is a prime.

It is not a weakly prime, because it can be changed into another prime (280541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 140280 + 140281.

It is an arithmetic number, because the mean of its divisors is an integer number (140281).

2²⁸⁰⁵⁶¹ is an apocalyptic number.

It is an amenable number.

280561 is a deficient number, since it is larger than the sum of its proper divisors (1).

280561 is an equidigital number, since it uses as much as digits as its factorization.

280561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 280561 is about 529.6800921311. The cubic root of 280561 is about 65.4649891561.

It can be divided in two parts, 280 and 561, that multiplied together give a triangular number (157080 = T₅₆₀).

The spelling of 280561 in words is "two hundred eighty thousand, five hundred sixty-one".