255993 has 4 divisors (see below), whose sum is σ = 341328. Its totient is φ = 170660.

The previous prime is 255989. The next prime is 256019. The reversal of 255993 is 399552.

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 255993 - 2² = 255989 is a prime.

It is a D-number.

It is not an unprimeable number, because it can be changed into a prime (255923) 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, 42663 + ... + 42668.

It is an arithmetic number, because the mean of its divisors is an integer number (85332).

2²⁵⁵⁹⁹³ is an apocalyptic number.

It is an amenable number.

255993 is a deficient number, since it is larger than the sum of its proper divisors (85335).

255993 is an equidigital number, since it uses as much as digits as its factorization.

255993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85334.

The product of its digits is 12150, while the sum is 33.

The square root of 255993 is about 505.9575080973. The cubic root of 255993 is about 63.4954633335.

The spelling of 255993 in words is "two hundred fifty-five thousand, nine hundred ninety-three".