255515561 has 4 divisors (see below), whose sum is σ = 292017792. Its totient is φ = 219013332.

The previous prime is 255515551. The next prime is 255515569. The reversal of 255515561 is 165515552.

It is a happy number.

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 a de Polignac number, because none of the positive numbers 2^k-255515561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (255515569) 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, 18251105 + ... + 18251118.

It is an arithmetic number, because the mean of its divisors is an integer number (73004448).

Almost surely, 2^255515561 is an apocalyptic number.

It is an amenable number.

255515561 is a deficient number, since it is larger than the sum of its proper divisors (36502231).

255515561 is an equidigital number, since it uses as much as digits as its factorization.

255515561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36502230.

The product of its digits is 37500, while the sum is 35.

The square root of 255515561 is about 15984.8541125654. The cubic root of 255515561 is about 634.5596475800.

Subtracting from 255515561 its reverse (165515552), we obtain a palindrome (90000009).

The spelling of 255515561 in words is "two hundred fifty-five million, five hundred fifteen thousand, five hundred sixty-one".