255990 has 64 divisors (see below), whose sum is σ = 746496. Its totient is φ = 54912.

The previous prime is 255989. The next prime is 256019. The reversal of 255990 is 99552.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4804 + ... + 4856.

It is an arithmetic number, because the mean of its divisors is an integer number (11664).

2²⁵⁵⁹⁹⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 255990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (373248).

255990 is an abundant number, since it is smaller than the sum of its proper divisors (490506).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

255990 is a wasteful number, since it uses less digits than its factorization.

255990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93.

The product of its (nonzero) digits is 4050, while the sum is 30.

The square root of 255990 is about 505.9545434127. The cubic root of 255990 is about 63.4952152966.

The spelling of 255990 in words is "two hundred fifty-five thousand, nine hundred ninety".