4005561 has 16 divisors (see below), whose sum is σ = 6425600. Its totient is φ = 2168208.

The previous prime is 4005553. The next prime is 4005613. The reversal of 4005561 is 1655004.

It is a happy number.

It is not a de Polignac number, because 4005561 - 2³ = 4005553 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Duffinian number.

4005561 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4000561) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4621 + ... + 5418.

It is an arithmetic number, because the mean of its divisors is an integer number (401600).

Almost surely, 2^4005561 is an apocalyptic number.

It is an amenable number.

4005561 is a deficient number, since it is larger than the sum of its proper divisors (2420039).

4005561 is a wasteful number, since it uses less digits than its factorization.

4005561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10068.

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 4005561 is about 2001.3897671368. The cubic root of 4005561 is about 158.8136339433.

The spelling of 4005561 in words is "four million, five thousand, five hundred sixty-one".