256991280 has 360 divisors, whose sum is σ = 1022965776. Its totient is φ = 52899840.

The previous prime is 256991257. The next prime is 256991299. The reversal of 256991280 is 82199652.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 6268060 + ... + 6268100.

Almost surely, 2^256991280 is an apocalyptic number.

256991280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256991280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (511482888).

256991280 is an abundant number, since it is smaller than the sum of its proper divisors (765974496).

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

256991280 is a wasteful number, since it uses less digits than its factorization.

256991280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125 (or 71 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 42.

The square root of 256991280 is about 16030.9475702467. The cubic root of 256991280 is about 635.7789271593.

The spelling of 256991280 in words is "two hundred fifty-six million, nine hundred ninety-one thousand, two hundred eighty".