65561 has 4 divisors (see below), whose sum is σ = 66852. Its totient is φ = 64272.

The previous prime is 65557. The next prime is 65563. The reversal of 65561 is 16556.

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

It can be written as a sum of positive squares in 2 ways, for example, as 48400 + 17161 = 220^2 + 131^2 .

It is a cyclic number.

It is not a de Polignac number, because 65561 - 2² = 65557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (65563) 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, 566 + ... + 671.

It is an arithmetic number, because the mean of its divisors is an integer number (16713).

2⁶⁵⁵⁶¹ is an apocalyptic number.

It is an amenable number.

65561 is a deficient number, since it is larger than the sum of its proper divisors (1291).

65561 is a wasteful number, since it uses less digits than its factorization.

65561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1290.

The product of its digits is 900, while the sum is 23.

The square root of 65561 is about 256.0488234693. The cubic root of 65561 is about 40.3225995768.

It can be divided in two parts, 65 and 561, that added together give a palindrome (626).

The spelling of 65561 in words is "sixty-five thousand, five hundred sixty-one".