255587921 has 2 divisors, whose sum is σ = 255587922. Its totient is φ = 255587920.

The previous prime is 255587869. The next prime is 255587923. The reversal of 255587921 is 129785552.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 135466321 + 120121600 = 11639^2 + 10960^2 .

It is a cyclic number.

It is not a de Polignac number, because 255587921 - 2¹⁰ = 255586897 is a prime.

It is a super-2 number, since 2×255587921² = 130650370722204482, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 255587923, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (255587923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 127793960 + 127793961.

It is an arithmetic number, because the mean of its divisors is an integer number (127793961).

Almost surely, 2^255587921 is an apocalyptic number.

It is an amenable number.

255587921 is a deficient number, since it is larger than the sum of its proper divisors (1).

255587921 is an equidigital number, since it uses as much as digits as its factorization.

255587921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 252000, while the sum is 44.

The square root of 255587921 is about 15987.1173449124. The cubic root of 255587921 is about 634.6195426958.

The spelling of 255587921 in words is "two hundred fifty-five million, five hundred eighty-seven thousand, nine hundred twenty-one".