1256139 has 6 divisors (see below), whose sum is σ = 1814436. Its totient is φ = 837420.

The previous prime is 1256107. The next prime is 1256149. The reversal of 1256139 is 9316521.

It is not a de Polignac number, because 1256139 - 2⁵ = 1256107 is a prime.

It is an Ulam number.

1256139 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1256149) 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 in 5 ways as a sum of consecutive naturals, for example, 69777 + ... + 69794.

It is an arithmetic number, because the mean of its divisors is an integer number (302406).

2^1256139 is an apocalyptic number.

1256139 is a deficient number, since it is larger than the sum of its proper divisors (558297).

1256139 is a wasteful number, since it uses less digits than its factorization.

1256139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139577 (or 139574 counting only the distinct ones).

The product of its digits is 1620, while the sum is 27.

The square root of 1256139 is about 1120.7760704084. The cubic root of 1256139 is about 107.8977942547.

The spelling of 1256139 in words is "one million, two hundred fifty-six thousand, one hundred thirty-nine".