256620261 has 4 divisors (see below), whose sum is σ = 342160352. Its totient is φ = 171080172.

The previous prime is 256620239. The next prime is 256620281. The reversal of 256620261 is 162026652.

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 not a de Polignac number, because 256620261 - 2²³ = 248231653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256620211) 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, 42770041 + ... + 42770046.

It is an arithmetic number, because the mean of its divisors is an integer number (85540088).

Almost surely, 2^256620261 is an apocalyptic number.

It is an amenable number.

256620261 is a deficient number, since it is larger than the sum of its proper divisors (85540091).

256620261 is an equidigital number, since it uses as much as digits as its factorization.

256620261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85540090.

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 256620261 is about 16019.3714296161. The cubic root of 256620261 is about 635.4728212228.

The spelling of 256620261 in words is "two hundred fifty-six million, six hundred twenty thousand, two hundred sixty-one".