255565421 has 2 divisors, whose sum is σ = 255565422. Its totient is φ = 255565420.

The previous prime is 255565399. The next prime is 255565493. The reversal of 255565421 is 124565552.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 255552196 + 13225 = 15986^2 + 115^2 .

It is a cyclic number.

It is not a de Polignac number, because 255565421 - 2⁶ = 255565357 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (255565621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 127782710 + 127782711.

It is an arithmetic number, because the mean of its divisors is an integer number (127782711).

Almost surely, 2^255565421 is an apocalyptic number.

It is an amenable number.

255565421 is a deficient number, since it is larger than the sum of its proper divisors (1).

255565421 is an equidigital number, since it uses as much as digits as its factorization.

255565421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 60000, while the sum is 35.

The square root of 255565421 is about 15986.4136378363. The cubic root of 255565421 is about 634.6009198039.

It can be divided in two parts, 2555 and 65421, that added together give a palindrome (67976).

The spelling of 255565421 in words is "two hundred fifty-five million, five hundred sixty-five thousand, four hundred twenty-one".