1256389 has 2 divisors, whose sum is σ = 1256390. Its totient is φ = 1256388.

The previous prime is 1256383. The next prime is 1256393. The reversal of 1256389 is 9836521.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 693889 + 562500 = 833^2 + 750^2 .

It is a cyclic number.

It is not a de Polignac number, because 1256389 - 2¹⁷ = 1125317 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1256383) by changing a digit.

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

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628194 + 628195.

It is an arithmetic number, because the mean of its divisors is an integer number (628195).

2^1256389 is an apocalyptic number.

It is an amenable number.

1256389 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256389 is an equidigital number, since it uses as much as digits as its factorization.

1256389 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 34.

The square root of 1256389 is about 1120.8875947213. The cubic root of 1256389 is about 107.9049518116.

The spelling of 1256389 in words is "one million, two hundred fifty-six thousand, three hundred eighty-nine".