256121517 has 4 divisors (see below), whose sum is σ = 341495360. Its totient is φ = 170747676.

The previous prime is 256121497. The next prime is 256121531. The reversal of 256121517 is 715121652.

256121517 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 256121517 - 2¹¹ = 256119469 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 (256191517) 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, 42686917 + ... + 42686922.

It is an arithmetic number, because the mean of its divisors is an integer number (85373840).

Almost surely, 2^256121517 is an apocalyptic number.

It is an amenable number.

256121517 is a deficient number, since it is larger than the sum of its proper divisors (85373843).

256121517 is an equidigital number, since it uses as much as digits as its factorization.

256121517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85373842.

The product of its digits is 4200, while the sum is 30.

The square root of 256121517 is about 16003.7969557227. The cubic root of 256121517 is about 635.0608716730.

The spelling of 256121517 in words is "two hundred fifty-six million, one hundred twenty-one thousand, five hundred seventeen".