256965391 has 4 divisors (see below), whose sum is σ = 258040800. Its totient is φ = 255889984.

The previous prime is 256965389. The next prime is 256965413. The reversal of 256965391 is 193569652.

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 256965391 - 2¹ = 256965389 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 (256965091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 537346 + ... + 537823.

It is an arithmetic number, because the mean of its divisors is an integer number (64510200).

Almost surely, 2^256965391 is an apocalyptic number.

256965391 is a deficient number, since it is larger than the sum of its proper divisors (1075409).

256965391 is a wasteful number, since it uses less digits than its factorization.

256965391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1075408.

The product of its digits is 437400, while the sum is 46.

The square root of 256965391 is about 16030.1400804859. The cubic root of 256965391 is about 635.7575772347.

The spelling of 256965391 in words is "two hundred fifty-six million, nine hundred sixty-five thousand, three hundred ninety-one".