256686978 has 32 divisors (see below), whose sum is σ = 556839360. Its totient is φ = 78563840.

The previous prime is 256686973. The next prime is 256687009. The reversal of 256686978 is 879686652.

It is not an unprimeable number, because it can be changed into a prime (256686973) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26508 + ... + 34871.

It is an arithmetic number, because the mean of its divisors is an integer number (17401230).

Almost surely, 2^256686978 is an apocalyptic number.

256686978 is an abundant number, since it is smaller than the sum of its proper divisors (300152382).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

256686978 is a wasteful number, since it uses less digits than its factorization.

256686978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61442.

The product of its digits is 8709120, while the sum is 57.

The square root of 256686978 is about 16021.4536793638. The cubic root of 256686978 is about 635.5278872393.

The spelling of 256686978 in words is "two hundred fifty-six million, six hundred eighty-six thousand, nine hundred seventy-eight".