1256271386691 has 8 divisors (see below), whose sum is σ = 1675101179664. Its totient is φ = 837477925760.

The previous prime is 1256271386647. The next prime is 1256271386707. The reversal of 1256271386691 is 1966831726521.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1256271386691 - 2¹⁷ = 1256271255619 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1256271386641) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 9002226 + ... + 9140711.

It is an arithmetic number, because the mean of its divisors is an integer number (209387647458).

Almost surely, 2^{1256271386691} is an apocalyptic number.

1256271386691 is a deficient number, since it is larger than the sum of its proper divisors (418829792973).

1256271386691 is a wasteful number, since it uses less digits than its factorization.

1256271386691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18166021.

The product of its digits is 6531840, while the sum is 57.

The spelling of 1256271386691 in words is "one trillion, two hundred fifty-six billion, two hundred seventy-one million, three hundred eighty-six thousand, six hundred ninety-one".