1256681 has 2 divisors, whose sum is σ = 1256682. Its totient is φ = 1256680.

The previous prime is 1256659. The next prime is 1256687. The reversal of 1256681 is 1866521.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1243225 + 13456 = 1115^2 + 116^2 .

It is an emirp because it is prime and its reverse (1866521) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1256681 - 2⁶ = 1256617 is a prime.

It is a super-2 number, since 2×1256681² = 3158494271522, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1256687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628340 + 628341.

It is an arithmetic number, because the mean of its divisors is an integer number (628341).

2^1256681 is an apocalyptic number.

It is an amenable number.

1256681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256681 is an equidigital number, since it uses as much as digits as its factorization.

1256681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2880, while the sum is 29.

The square root of 1256681 is about 1121.0178410712. The cubic root of 1256681 is about 107.9133106360.

The spelling of 1256681 in words is "one million, two hundred fifty-six thousand, six hundred eighty-one".