256217920 has 112 divisors (see below), whose sum is σ = 704453760. Its totient is φ = 86943744.

The previous prime is 256217909. The next prime is 256217947. The reversal of 256217920 is 29712652.

It is a tau number, because it is divible by the number of its divisors (112).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 239146 + ... + 240214.

Almost surely, 2^256217920 is an apocalyptic number.

256217920 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 256217920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (352226880).

256217920 is an abundant number, since it is smaller than the sum of its proper divisors (448235840).

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

256217920 is a wasteful number, since it uses less digits than its factorization.

256217920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1200 (or 1190 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 256217920 is about 16006.8085513634. The cubic root of 256217920 is about 635.1405397076.

The spelling of 256217920 in words is "two hundred fifty-six million, two hundred seventeen thousand, nine hundred twenty".