256105405 has 4 divisors (see below), whose sum is σ = 307326492. Its totient is φ = 204884320.

The previous prime is 256105387. The next prime is 256105441. The reversal of 256105405 is 504501652.

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 117548964 + 138556441 = 10842^2 + 11771^2 .

It is not a de Polignac number, because 256105405 - 2⁵ = 256105373 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 25610536 + ... + 25610545.

It is an arithmetic number, because the mean of its divisors is an integer number (76831623).

Almost surely, 2^256105405 is an apocalyptic number.

It is an amenable number.

256105405 is a deficient number, since it is larger than the sum of its proper divisors (51221087).

256105405 is an equidigital number, since it uses as much as digits as its factorization.

256105405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51221086.

The product of its (nonzero) digits is 6000, while the sum is 28.

The square root of 256105405 is about 16003.2935672630. The cubic root of 256105405 is about 635.0475546670.

The spelling of 256105405 in words is "two hundred fifty-six million, one hundred five thousand, four hundred five".