5561661 has 32 divisors (see below), whose sum is σ = 9123840. Its totient is φ = 2942784.

The previous prime is 5561659. The next prime is 5561687. The reversal of 5561661 is 1661655.

It is not a de Polignac number, because 5561661 - 2¹ = 5561659 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (5561641) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21016 + ... + 21278.

It is an arithmetic number, because the mean of its divisors is an integer number (285120).

Almost surely, 2^5561661 is an apocalyptic number.

It is an amenable number.

5561661 is a deficient number, since it is larger than the sum of its proper divisors (3562179).

5561661 is a wasteful number, since it uses less digits than its factorization.

5561661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 345.

The product of its digits is 5400, while the sum is 30.

The square root of 5561661 is about 2358.3174086624. The cubic root of 5561661 is about 177.1746178062.

It can be divided in two parts, 55 and 61661, that added together give a palindrome (61716).

The spelling of 5561661 in words is "five million, five hundred sixty-one thousand, six hundred sixty-one".