256778239181 has 4 divisors (see below), whose sum is σ = 256941689664. Its totient is φ = 256614788700.

The previous prime is 256778239171. The next prime is 256778239231. The reversal of 256778239181 is 181932877652.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256778239181 is a prime.

It is a super-2 number, since 2×256778239181² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 256778239181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256778239171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 81722885 + ... + 81726026.

It is an arithmetic number, because the mean of its divisors is an integer number (64235422416).

Almost surely, 2^256778239181 is an apocalyptic number.

It is an amenable number.

256778239181 is a deficient number, since it is larger than the sum of its proper divisors (163450483).

256778239181 is a wasteful number, since it uses less digits than its factorization.

256778239181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163450482.

The product of its digits is 10160640, while the sum is 59.

The spelling of 256778239181 in words is "two hundred fifty-six billion, seven hundred seventy-eight million, two hundred thirty-nine thousand, one hundred eighty-one".