1256891 has 2 divisors, whose sum is σ = 1256892. Its totient is φ = 1256890.

The previous prime is 1256887. The next prime is 1256897. The reversal of 1256891 is 1986521.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1256891 - 2² = 1256887 is a prime.

It is an Ulam number.

It is not a weakly prime, because it can be changed into another prime (1256897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628445 + 628446.

It is an arithmetic number, because the mean of its divisors is an integer number (628446).

2^1256891 is an apocalyptic number.

1256891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256891 is an equidigital number, since it uses as much as digits as its factorization.

1256891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 32.

The square root of 1256891 is about 1121.1115020372. Note that the first 3 decimals coincide. The cubic root of 1256891 is about 107.9193213190.

The spelling of 1256891 in words is "one million, two hundred fifty-six thousand, eight hundred ninety-one".