55561 has 4 divisors (see below), whose sum is σ = 60624. Its totient is φ = 50500.

The previous prime is 55547. The next prime is 55579. The reversal of 55561 is 16555.

55561 = 66² + 67² + ... + 76².

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 55561 - 2⁵ = 55529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2515 + ... + 2536.

It is an arithmetic number, because the mean of its divisors is an integer number (15156).

2⁵⁵⁵⁶¹ is an apocalyptic number.

It is an amenable number.

55561 is a deficient number, since it is larger than the sum of its proper divisors (5063).

55561 is a wasteful number, since it uses less digits than its factorization.

55561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5062.

The product of its digits is 750, while the sum is 22.

The square root of 55561 is about 235.7138095233. The cubic root of 55561 is about 38.1583878443.

It can be divided in two parts, 555 and 61, that added together give a palindrome (616).

The spelling of 55561 in words is "fifty-five thousand, five hundred sixty-one".