256722917171 has 4 divisors (see below), whose sum is σ = 293397619632. Its totient is φ = 220048214712.

The previous prime is 256722917117. The next prime is 256722917197. The reversal of 256722917171 is 171719227652.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256722917171 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256722917771) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18337351220 + ... + 18337351233.

It is an arithmetic number, because the mean of its divisors is an integer number (73349404908).

Almost surely, 2^256722917171 is an apocalyptic number.

256722917171 is a deficient number, since it is larger than the sum of its proper divisors (36674702461).

256722917171 is an equidigital number, since it uses as much as digits as its factorization.

256722917171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36674702460.

The product of its digits is 740880, while the sum is 50.

The spelling of 256722917171 in words is "two hundred fifty-six billion, seven hundred twenty-two million, nine hundred seventeen thousand, one hundred seventy-one".