255639 has 4 divisors (see below), whose sum is σ = 340856. Its totient is φ = 170424.

The previous prime is 255637. The next prime is 255641. The reversal of 255639 is 936552.

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

It is an interprime number because it is at equal distance from previous prime (255637) and next prime (255641).

It is not a de Polignac number, because 255639 - 2¹ = 255637 is a prime.

It is an Ulam number.

It is a D-number.

It is a Duffinian number.

255639 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (255637) 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, 42604 + ... + 42609.

It is an arithmetic number, because the mean of its divisors is an integer number (85214).

2²⁵⁵⁶³⁹ is an apocalyptic number.

255639 is a deficient number, since it is larger than the sum of its proper divisors (85217).

255639 is an equidigital number, since it uses as much as digits as its factorization.

255639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85216.

The product of its digits is 8100, while the sum is 30.

The square root of 255639 is about 505.6075553233. The cubic root of 255639 is about 63.4661815915.

The spelling of 255639 in words is "two hundred fifty-five thousand, six hundred thirty-nine".