256081261 has 4 divisors (see below), whose sum is σ = 258721372. Its totient is φ = 253441152.

The previous prime is 256081253. The next prime is 256081271. The reversal of 256081261 is 162180652.

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

It can be written as a sum of positive squares in 2 ways, for example, as 128255625 + 127825636 = 11325^2 + 11306^2 .

It is a cyclic number.

It is not a de Polignac number, because 256081261 - 2³ = 256081253 is a prime.

It is a super-2 number, since 2×256081261² = 131155224470700242, which 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 (256081271) 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, 1319910 + ... + 1320103.

It is an arithmetic number, because the mean of its divisors is an integer number (64680343).

Almost surely, 2^256081261 is an apocalyptic number.

It is an amenable number.

256081261 is a deficient number, since it is larger than the sum of its proper divisors (2640111).

256081261 is an equidigital number, since it uses as much as digits as its factorization.

256081261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2640110.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 256081261 is about 16002.5392047637. The cubic root of 256081261 is about 635.0275979491.

The spelling of 256081261 in words is "two hundred fifty-six million, eighty-one thousand, two hundred sixty-one".