1256536881 has 20 divisors (see below), whose sum is σ = 1922835684. Its totient is φ = 817257600.

The previous prime is 1256536867. The next prime is 1256536889. The reversal of 1256536881 is 1886356521.

1256536881 is a `hidden beast` number, since 1 + 2 + 565 + 3 + 6 + 8 + 81 = 666.

1256536881 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 447703281 + 808833600 = 21159^2 + 28440^2 .

It is not a de Polignac number, because 1256536881 - 2¹¹ = 1256534833 is a prime.

It is a super-2 number, since 2×1256536881² = 3157769866626416322, which contains 22 as substring.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (1256536889) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 185860 + ... + 192501.

Almost surely, 2^1256536881 is an apocalyptic number.

It is an amenable number.

1256536881 is a deficient number, since it is larger than the sum of its proper divisors (666298803).

1256536881 is an equidigital number, since it uses as much as digits as its factorization.

1256536881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 378414 (or 378405 counting only the distinct ones).

The product of its digits is 345600, while the sum is 45.

The square root of 1256536881 is about 35447.6639709869. The cubic root of 1256536881 is about 1079.0918523138.

The spelling of 1256536881 in words is "one billion, two hundred fifty-six million, five hundred thirty-six thousand, eight hundred eighty-one".