255998921 has 4 divisors (see below), whose sum is σ = 264826500. Its totient is φ = 247171344.

The previous prime is 255998917. The next prime is 255998929. The reversal of 255998921 is 129899552.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 58736896 + 197262025 = 7664^2 + 14045^2 .

It is a cyclic number.

It is not a de Polignac number, because 255998921 - 2² = 255998917 is a prime.

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 255998921.

It is not an unprimeable number, because it can be changed into a prime (255998929) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4413746 + ... + 4413803.

It is an arithmetic number, because the mean of its divisors is an integer number (66206625).

Almost surely, 2^255998921 is an apocalyptic number.

It is an amenable number.

255998921 is a deficient number, since it is larger than the sum of its proper divisors (8827579).

255998921 is an equidigital number, since it uses as much as digits as its factorization.

255998921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8827578.

The product of its digits is 583200, while the sum is 50.

The square root of 255998921 is about 15999.9662812145. The cubic root of 255998921 is about 634.9595286997.

The spelling of 255998921 in words is "two hundred fifty-five million, nine hundred ninety-eight thousand, nine hundred twenty-one".