255561 has 8 divisors (see below), whose sum is σ = 360864. Its totient is φ = 160320.

The previous prime is 255551. The next prime is 255571. The reversal of 255561 is 165552.

It is an interprime number because it is at equal distance from previous prime (255551) and next prime (255571).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 255561 - 2⁹ = 255049 is a prime.

It is a super-2 number, since 2×255561² = 130622849442, which contains 22 as substring.

It is a Curzon number.

255561 is a lucky number.

It is a nialpdrome in base 8.

It is not an unprimeable number, because it can be changed into a prime (255511) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2455 + ... + 2556.

It is an arithmetic number, because the mean of its divisors is an integer number (45108).

2²⁵⁵⁵⁶¹ is an apocalyptic number.

It is an amenable number.

255561 is a deficient number, since it is larger than the sum of its proper divisors (105303).

255561 is a wasteful number, since it uses less digits than its factorization.

255561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5031.

The product of its digits is 1500, while the sum is 24.

The square root of 255561 is about 505.5304145153. The cubic root of 255561 is about 63.4597260484.

Subtracting from 255561 its reverse (165552), we obtain a palindrome (90009).

The spelling of 255561 in words is "two hundred fifty-five thousand, five hundred sixty-one".