256399939 has 2 divisors, whose sum is σ = 256399940. Its totient is φ = 256399938.

The previous prime is 256399901. The next prime is 256399961. The reversal of 256399939 is 939993652.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 256399939 - 2¹¹ = 256397891 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 256399939.

It is not a weakly prime, because it can be changed into another prime (256399999) 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, 128199969 + 128199970.

It is an arithmetic number, because the mean of its divisors is an integer number (128199970).

Almost surely, 2^256399939 is an apocalyptic number.

256399939 is a deficient number, since it is larger than the sum of its proper divisors (1).

256399939 is an equidigital number, since it uses as much as digits as its factorization.

256399939 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3542940, while the sum is 55.

The square root of 256399939 is about 16012.4932162359. The cubic root of 256399939 is about 635.2909068645.

The spelling of 256399939 in words is "two hundred fifty-six million, three hundred ninety-nine thousand, nine hundred thirty-nine".