255551 has 2 divisors, whose sum is σ = 255552. Its totient is φ = 255550.

The previous prime is 255523. The next prime is 255571. The reversal of 255551 is 155552.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 255551 - 2⁶ = 255487 is a prime.

It is an Ulam number.

It is equal to p₂₂₄₈₇ and since 255551 and 22487 have the same sum of digits, it is a Honaker prime.

It is a zygodrome in base 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (255511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 127775 + 127776.

It is an arithmetic number, because the mean of its divisors is an integer number (127776).

2²⁵⁵⁵⁵¹ is an apocalyptic number.

255551 is a deficient number, since it is larger than the sum of its proper divisors (1).

255551 is an equidigital number, since it uses as much as digits as its factorization.

255551 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1250, while the sum is 23.

The square root of 255551 is about 505.5205238168. The cubic root of 255551 is about 63.4588983197.

Subtracting from 255551 its reverse (155552), we obtain a palindrome (99999).

It can be divided in two parts, 2555 and 51, that multiplied together give a triangular number (130305 = T₅₁₀).

The spelling of 255551 in words is "two hundred fifty-five thousand, five hundred fifty-one".