255999 has 4 divisors (see below), whose sum is σ = 341336. Its totient is φ = 170664.

The previous prime is 255989. The next prime is 256019. The reversal of 255999 is 999552.

255999 = T₂₃₄ + T₂₃₅ + ... + T₂₄₂.

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

It is not a de Polignac number, because 255999 - 2⁸ = 255743 is a prime.

It is a D-number.

It is a Duffinian number.

255999 is a modest number, since divided by 999 gives 255 as remainder.

255999 is a lucky number.

It is a plaindrome in base 10.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (255919) 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, 42664 + ... + 42669.

It is an arithmetic number, because the mean of its divisors is an integer number (85334).

2²⁵⁵⁹⁹⁹ is an apocalyptic number.

255999 is a deficient number, since it is larger than the sum of its proper divisors (85337).

255999 is an equidigital number, since it uses as much as digits as its factorization.

255999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85336.

The product of its digits is 36450, while the sum is 39.

The square root of 255999 is about 505.9634374142. The cubic root of 255999 is about 63.4959594015.

The spelling of 255999 in words is "two hundred fifty-five thousand, nine hundred ninety-nine".