1808561 has 2 divisors, whose sum is σ = 1808562. Its totient is φ = 1808560.

The previous prime is 1808557. The next prime is 1808567. The reversal of 1808561 is 1658081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1168561 + 640000 = 1081^2 + 800^2 .

It is a cyclic number.

It is not a de Polignac number, because 1808561 - 2² = 1808557 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1808567) 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 as a sum of consecutive naturals, namely, 904280 + 904281.

It is an arithmetic number, because the mean of its divisors is an integer number (904281).

2^1808561 is an apocalyptic number.

It is an amenable number.

1808561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1808561 is an equidigital number, since it uses as much as digits as its factorization.

1808561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1920, while the sum is 29.

The square root of 1808561 is about 1344.8274982317. The cubic root of 1808561 is about 121.8365858333.

The spelling of 1808561 in words is "one million, eight hundred eight thousand, five hundred sixty-one".