256557139 has 2 divisors, whose sum is σ = 256557140. Its totient is φ = 256557138.

The previous prime is 256557109. The next prime is 256557163. The reversal of 256557139 is 931755652.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 256557139 - 2⁹ = 256556627 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 256557095 and 256557104.

It is not a weakly prime, because it can be changed into another prime (256557109) 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, 128278569 + 128278570.

It is an arithmetic number, because the mean of its divisors is an integer number (128278570).

Almost surely, 2^256557139 is an apocalyptic number.

256557139 is a deficient number, since it is larger than the sum of its proper divisors (1).

256557139 is an equidigital number, since it uses as much as digits as its factorization.

256557139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 283500, while the sum is 43.

The square root of 256557139 is about 16017.4011312697. The cubic root of 256557139 is about 635.4207136137.

The spelling of 256557139 in words is "two hundred fifty-six million, five hundred fifty-seven thousand, one hundred thirty-nine".