255990861 has 40 divisors (see below), whose sum is σ = 438387840. Its totient is φ = 145828512.

The previous prime is 255990817. The next prime is 255990869. The reversal of 255990861 is 168099552.

255990861 is a `hidden beast` number, since 2 + 559 + 90 + 8 + 6 + 1 = 666.

It is not a de Polignac number, because 255990861 - 2⁶ = 255990797 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (255990869) 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 in 39 ways as a sum of consecutive naturals, for example, 288160 + ... + 289046.

It is an arithmetic number, because the mean of its divisors is an integer number (10959696).

Almost surely, 2^255990861 is an apocalyptic number.

255990861 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

255990861 is a deficient number, since it is larger than the sum of its proper divisors (182396979).

255990861 is an equidigital number, since it uses as much as digits as its factorization.

255990861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1415 (or 1406 counting only the distinct ones).

The product of its (nonzero) digits is 194400, while the sum is 45.

The square root of 255990861 is about 15999.7144037011. The cubic root of 255990861 is about 634.9528648337.

The spelling of 255990861 in words is "two hundred fifty-five million, nine hundred ninety thousand, eight hundred sixty-one".