255320821 has 6 divisors (see below), whose sum is σ = 297005910. Its totient is φ = 218846376.

The previous prime is 255320809. The next prime is 255320851. The reversal of 255320821 is 128023552.

It can be written as a sum of positive squares in only one way, i.e., 253159921 + 2160900 = 15911^2 + 1470^2 .

It is not a de Polignac number, because 255320821 - 2⁷ = 255320693 is a prime.

It is a super-2 number, since 2×255320821² = 130377443272228082, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 255320821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (255320801) 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 in 5 ways as a sum of consecutive naturals, for example, 2605266 + ... + 2605363.

It is an arithmetic number, because the mean of its divisors is an integer number (49500985).

Almost surely, 2^255320821 is an apocalyptic number.

It is an amenable number.

255320821 is a deficient number, since it is larger than the sum of its proper divisors (41685089).

255320821 is an equidigital number, since it uses as much as digits as its factorization.

255320821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5210643 (or 5210636 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 255320821 is about 15978.7615602712. The cubic root of 255320821 is about 634.3983977101.

The spelling of 255320821 in words is "two hundred fifty-five million, three hundred twenty thousand, eight hundred twenty-one".