256117551 has 8 divisors (see below), whose sum is σ = 344512560. Its totient is φ = 169233792.

The previous prime is 256117541. The next prime is 256117559. The reversal of 256117551 is 155711652.

It is a happy number.

256117551 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 256117551 - 2⁷ = 256117423 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256117559) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 377416 + ... + 378093.

It is an arithmetic number, because the mean of its divisors is an integer number (43064070).

Almost surely, 2^256117551 is an apocalyptic number.

256117551 is a deficient number, since it is larger than the sum of its proper divisors (88395009).

256117551 is a wasteful number, since it uses less digits than its factorization.

256117551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 755625.

The product of its digits is 10500, while the sum is 33.

The square root of 256117551 is about 16003.6730471476. The cubic root of 256117551 is about 635.0575937180.

The spelling of 256117551 in words is "two hundred fifty-six million, one hundred seventeen thousand, five hundred fifty-one".