256778239171 has 2 divisors, whose sum is σ = 256778239172. Its totient is φ = 256778239170.

The previous prime is 256778239169. The next prime is 256778239231. The reversal of 256778239171 is 171932877652.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 256778239171 - 2¹ = 256778239169 is a prime.

It is a super-2 number, since 2×256778239171² (a number of 24 digits) contains 22 as substring.

Together with 256778239169, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (256778239871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128389119585 + 128389119586.

It is an arithmetic number, because the mean of its divisors is an integer number (128389119586).

Almost surely, 2^256778239171 is an apocalyptic number.

256778239171 is a deficient number, since it is larger than the sum of its proper divisors (1).

256778239171 is an equidigital number, since it uses as much as digits as its factorization.

256778239171 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8890560, while the sum is 58.

The spelling of 256778239171 in words is "two hundred fifty-six billion, seven hundred seventy-eight million, two hundred thirty-nine thousand, one hundred seventy-one".