256560491 has 4 divisors (see below), whose sum is σ = 279884184. Its totient is φ = 233236800.

The previous prime is 256560467. The next prime is 256560517. The reversal of 256560491 is 194065652.

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

It is a cyclic number.

It is not a de Polignac number, because 256560491 - 2¹⁰ = 256559467 is a prime.

It is a super-2 number, since 2×256560491² = 131646571084322162, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256560461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11661830 + ... + 11661851.

It is an arithmetic number, because the mean of its divisors is an integer number (69971046).

Almost surely, 2^256560491 is an apocalyptic number.

256560491 is a deficient number, since it is larger than the sum of its proper divisors (23323693).

256560491 is a wasteful number, since it uses less digits than its factorization.

256560491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23323692.

The product of its (nonzero) digits is 64800, while the sum is 38.

The square root of 256560491 is about 16017.5057671287. The cubic root of 256560491 is about 635.4234809257.

The spelling of 256560491 in words is "two hundred fifty-six million, five hundred sixty thousand, four hundred ninety-one".