256778 has 4 divisors (see below), whose sum is σ = 385170. Its totient is φ = 128388.

The previous prime is 256771. The next prime is 256799. The reversal of 256778 is 877652.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 139129 + 117649 = 373^2 + 343^2 .

It is a plaindrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (256771) by changing a digit.

256778 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64193 + ... + 64196.

2²⁵⁶⁷⁷⁸ is an apocalyptic number.

256778 is a deficient number, since it is larger than the sum of its proper divisors (128392).

256778 is a wasteful number, since it uses less digits than its factorization.

256778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128391.

The product of its digits is 23520, while the sum is 35.

The square root of 256778 is about 506.7326711393. The cubic root of 256778 is about 63.5602998416.

The spelling of 256778 in words is "two hundred fifty-six thousand, seven hundred seventy-eight".