256007781 has 6 divisors (see below), whose sum is σ = 369789030. Its totient is φ = 170671848.

The previous prime is 256007771. The next prime is 256007819. The reversal of 256007781 is 187700652.

It can be written as a sum of positive squares in only one way, i.e., 168117156 + 87890625 = 12966^2 + 9375^2 .

It is not a de Polignac number, because 256007781 - 2⁵ = 256007749 is a prime.

It is a super-2 number, since 2×256007781² = 131079967865087922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256007711) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 14222646 + ... + 14222663.

It is an arithmetic number, because the mean of its divisors is an integer number (61631505).

Almost surely, 2^256007781 is an apocalyptic number.

It is an amenable number.

256007781 is a deficient number, since it is larger than the sum of its proper divisors (113781249).

256007781 is a wasteful number, since it uses less digits than its factorization.

256007781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28445315 (or 28445312 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 36.

The square root of 256007781 is about 16000.2431544024. The cubic root of 256007781 is about 634.9668538302.

The spelling of 256007781 in words is "two hundred fifty-six million, seven thousand, seven hundred eighty-one".