256991378 has 32 divisors (see below), whose sum is σ = 473232000. Its totient is φ = 104337072.

The previous prime is 256991377. The next prime is 256991407. The reversal of 256991378 is 873199652.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256991377) 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, 3176 + ... + 22892.

It is an arithmetic number, because the mean of its divisors is an integer number (14788500).

Almost surely, 2^256991378 is an apocalyptic number.

256991378 is a deficient number, since it is larger than the sum of its proper divisors (216240622).

256991378 is a wasteful number, since it uses less digits than its factorization.

256991378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19759 (or 19745 counting only the distinct ones).

The product of its digits is 816480, while the sum is 50.

The square root of 256991378 is about 16030.9506268343. The cubic root of 256991378 is about 635.7790079744.

The spelling of 256991378 in words is "two hundred fifty-six million, nine hundred ninety-one thousand, three hundred seventy-eight".