256989551 has 16 divisors (see below), whose sum is σ = 319437888. Its totient is φ = 201312000.

The previous prime is 256989533. The next prime is 256989559. The reversal of 256989551 is 155989652.

It is a cyclic number.

It is not a de Polignac number, because 256989551 - 2⁶ = 256989487 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 256989551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256989559) 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 15 ways as a sum of consecutive naturals, for example, 4790 + ... + 23171.

It is an arithmetic number, because the mean of its divisors is an integer number (19964868).

Almost surely, 2^256989551 is an apocalyptic number.

256989551 is a deficient number, since it is larger than the sum of its proper divisors (62448337).

256989551 is a wasteful number, since it uses less digits than its factorization.

256989551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28082.

The product of its digits is 972000, while the sum is 50.

The square root of 256989551 is about 16030.8936432128. The cubic root of 256989551 is about 635.7775013467. Note that the first 3 decimals are identical.

The spelling of 256989551 in words is "two hundred fifty-six million, nine hundred eighty-nine thousand, five hundred fifty-one".