1820561 has 4 divisors (see below), whose sum is σ = 1916400. Its totient is φ = 1724724.

The previous prime is 1820557. The next prime is 1820573. The reversal of 1820561 is 1650281.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1820561 - 2² = 1820557 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1820501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47891 + ... + 47928.

It is an arithmetic number, because the mean of its divisors is an integer number (479100).

2^1820561 is an apocalyptic number.

It is an amenable number.

1820561 is a deficient number, since it is larger than the sum of its proper divisors (95839).

1820561 is an equidigital number, since it uses as much as digits as its factorization.

1820561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95838.

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 1820561 is about 1349.2816607366. The cubic root of 1820561 is about 122.1054583976.

The spelling of 1820561 in words is "one million, eight hundred twenty thousand, five hundred sixty-one".