561655 has 4 divisors (see below), whose sum is σ = 673992. Its totient is φ = 449320.

The previous prime is 561607. The next prime is 561667. The reversal of 561655 is 556165.

561655 is nontrivially palindromic in base 9.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 561655 - 2¹³ = 553463 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 56161 + ... + 56170.

It is an arithmetic number, because the mean of its divisors is an integer number (168498).

2⁵⁶¹⁶⁵⁵ is an apocalyptic number.

561655 is a deficient number, since it is larger than the sum of its proper divisors (112337).

561655 is a wasteful number, since it uses less digits than its factorization.

561655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112336.

The product of its digits is 4500, while the sum is 28.

The square root of 561655 is about 749.4364549446. The cubic root of 561655 is about 82.5068252694.

It can be divided in two parts, 5616 and 55, that added together give a triangular number (5671 = T₁₀₆).

The spelling of 561655 in words is "five hundred sixty-one thousand, six hundred fifty-five".