256399784 has 8 divisors (see below), whose sum is σ = 480749610. Its totient is φ = 128199888.

The previous prime is 256399783. The next prime is 256399799. The reversal of 256399784 is 487993652.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 163277284 + 93122500 = 12778^2 + 9650^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (256399783) 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, 16024979 + ... + 16024994.

Almost surely, 2^256399784 is an apocalyptic number.

It is an amenable number.

256399784 is a deficient number, since it is larger than the sum of its proper divisors (224349826).

256399784 is a wasteful number, since it uses less digits than its factorization.

256399784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32049979 (or 32049975 counting only the distinct ones).

The product of its digits is 3265920, while the sum is 53.

The square root of 256399784 is about 16012.4883762643. The cubic root of 256399784 is about 635.2907788482.

The spelling of 256399784 in words is "two hundred fifty-six million, three hundred ninety-nine thousand, seven hundred eighty-four".