2005561 has 4 divisors (see below), whose sum is σ = 2009124. Its totient is φ = 2002000.

The previous prime is 2005559. The next prime is 2005567. The reversal of 2005561 is 1655002.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1655002 = 2 ⋅827501.

It can be written as a sum of positive squares in 2 ways, for example, as 1452025 + 553536 = 1205^2 + 744^2 .

It is a cyclic number.

It is not a de Polignac number, because 2005561 - 2¹ = 2005559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2005567) 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, 730 + ... + 2131.

It is an arithmetic number, because the mean of its divisors is an integer number (502281).

2^2005561 is an apocalyptic number.

It is an amenable number.

2005561 is a deficient number, since it is larger than the sum of its proper divisors (3563).

2005561 is an equidigital number, since it uses as much as digits as its factorization.

2005561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3562.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 2005561 is about 1416.1783079824. The cubic root of 2005561 is about 126.1087706093.

The spelling of 2005561 in words is "two million, five thousand, five hundred sixty-one".