256666781253 has 16 divisors (see below), whose sum is σ = 344437554240. Its totient is φ = 170007023616.

The previous prime is 256666781219. The next prime is 256666781353. The reversal of 256666781253 is 352187666652.

It is not a de Polignac number, because 256666781253 - 2¹³ = 256666773061 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 256666781193 and 256666781202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256666781353) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 127975 + ... + 727812.

It is an arithmetic number, because the mean of its divisors is an integer number (21527347140).

Almost surely, 2^256666781253 is an apocalyptic number.

It is an amenable number.

256666781253 is a deficient number, since it is larger than the sum of its proper divisors (87770772987).

256666781253 is a wasteful number, since it uses less digits than its factorization.

256666781253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 856436.

The product of its digits is 21772800, while the sum is 57.

The spelling of 256666781253 in words is "two hundred fifty-six billion, six hundred sixty-six million, seven hundred eighty-one thousand, two hundred fifty-three".