280005821 has 2 divisors, whose sum is σ = 280005822. Its totient is φ = 280005820.

The previous prime is 280005787. The next prime is 280005823. The reversal of 280005821 is 128500082.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 279357796 + 648025 = 16714^2 + 805^2 .

It is a cyclic number.

It is not a de Polignac number, because 280005821 - 2⁶ = 280005757 is a prime.

Together with 280005823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (280005823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 140002910 + 140002911.

It is an arithmetic number, because the mean of its divisors is an integer number (140002911).

Almost surely, 2^280005821 is an apocalyptic number.

It is an amenable number.

280005821 is a deficient number, since it is larger than the sum of its proper divisors (1).

280005821 is an equidigital number, since it uses as much as digits as its factorization.

280005821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1280, while the sum is 26.

The square root of 280005821 is about 16733.3744654209. The cubic root of 280005821 is about 654.2177955484.

The spelling of 280005821 in words is "two hundred eighty million, five thousand, eight hundred twenty-one".