205551 has 16 divisors (see below), whose sum is σ = 318720. Its totient is φ = 130680.

The previous prime is 205549. The next prime is 205553. The reversal of 205551 is 155502.

It is an interprime number because it is at equal distance from previous prime (205549) and next prime (205553).

It is not a de Polignac number, because 205551 - 2¹ = 205549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 456 + ... + 786.

It is an arithmetic number, because the mean of its divisors is an integer number (19920).

2²⁰⁵⁵⁵¹ is an apocalyptic number.

205551 is a deficient number, since it is larger than the sum of its proper divisors (113169).

205551 is a wasteful number, since it uses less digits than its factorization.

205551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 363 (or 357 counting only the distinct ones).

The product of its (nonzero) digits is 250, while the sum is 18.

The square root of 205551 is about 453.3773262968. The cubic root of 205551 is about 59.0164657672.

The spelling of 205551 in words is "two hundred five thousand, five hundred fifty-one".