256745265661641 has 4 divisors (see below), whose sum is σ = 342327020882192. Its totient is φ = 171163510441092.

The previous prime is 256745265661637. The next prime is 256745265661657. The reversal of 256745265661641 is 146166562547652.

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 256745265661641 - 2² = 256745265661637 is a prime.

It is a super-2 number, since 2×256745265661641² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256745265621641) 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, 42790877610271 + ... + 42790877610276.

It is an arithmetic number, because the mean of its divisors is an integer number (85581755220548).

Almost surely, 2^{256745265661641} is an apocalyptic number.

It is an amenable number.

256745265661641 is a deficient number, since it is larger than the sum of its proper divisors (85581755220551).

256745265661641 is an equidigital number, since it uses as much as digits as its factorization.

256745265661641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85581755220550.

The product of its digits is 435456000, while the sum is 66.

The spelling of 256745265661641 in words is "two hundred fifty-six trillion, seven hundred forty-five billion, two hundred sixty-five million, six hundred sixty-one thousand, six hundred forty-one".