256950581581 has 32 divisors (see below), whose sum is σ = 281544167520. Its totient is φ = 233515892736.

The previous prime is 256950581557. The next prime is 256950581617. The reversal of 256950581581 is 185185059652.

256950581581 = 358434² + 358435².

It can be written as a sum of positive squares in 16 ways, for example, as 8008460100 + 248942121481 = 89490^2 + 498941^2 .

It is a 7-Lehmer number, since φ(256950581581) divides (256950581581-1)⁷.

It is a cyclic number.

It is not a de Polignac number, because 256950581581 - 2¹³ = 256950573389 is a prime.

It is a super-2 number, since 2×256950581581² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256950581501) 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 31 ways as a sum of consecutive naturals, for example, 53651935 + ... + 53656723.

It is an arithmetic number, because the mean of its divisors is an integer number (8798255235).

Almost surely, 2^256950581581 is an apocalyptic number.

256950581581 is the 358435-th centered square number.

It is an amenable number.

256950581581 is a deficient number, since it is larger than the sum of its proper divisors (24593585939).

256950581581 is a wasteful number, since it uses less digits than its factorization.

256950581581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5473.

The product of its (nonzero) digits is 4320000, while the sum is 55.

The spelling of 256950581581 in words is "two hundred fifty-six billion, nine hundred fifty million, five hundred eighty-one thousand, five hundred eighty-one".