1256399 has 4 divisors (see below), whose sum is σ = 1296960. Its totient is φ = 1215840.

The previous prime is 1256393. The next prime is 1256407. The reversal of 1256399 is 9936521.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1256399 - 2⁴ = 1256383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1256393) 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 in 3 ways as a sum of consecutive naturals, for example, 20234 + ... + 20295.

It is an arithmetic number, because the mean of its divisors is an integer number (324240).

2^1256399 is an apocalyptic number.

1256399 is a deficient number, since it is larger than the sum of its proper divisors (40561).

1256399 is an equidigital number, since it uses as much as digits as its factorization.

1256399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40560.

The product of its digits is 14580, while the sum is 35.

The square root of 1256399 is about 1120.8920554630. The cubic root of 1256399 is about 107.9052380941.

The spelling of 1256399 in words is "one million, two hundred fifty-six thousand, three hundred ninety-nine".