256512240561 has 4 divisors (see below), whose sum is σ = 342016320752. Its totient is φ = 171008160372.

The previous prime is 256512240533. The next prime is 256512240587. The reversal of 256512240561 is 165042215652.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 256512240561 - 2¹⁰ = 256512239537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256512240521) 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, 42752040091 + ... + 42752040096.

It is an arithmetic number, because the mean of its divisors is an integer number (85504080188).

Almost surely, 2^256512240561 is an apocalyptic number.

It is an amenable number.

256512240561 is a deficient number, since it is larger than the sum of its proper divisors (85504080191).

256512240561 is an equidigital number, since it uses as much as digits as its factorization.

256512240561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85504080190.

The product of its (nonzero) digits is 144000, while the sum is 39.

The spelling of 256512240561 in words is "two hundred fifty-six billion, five hundred twelve million, two hundred forty thousand, five hundred sixty-one".