256668720 has 640 divisors, whose sum is σ = 1131356160. Its totient is φ = 46448640.

The previous prime is 256668719. The next prime is 256668721. The reversal of 256668720 is 27866652.

It is an interprime number because it is at equal distance from previous prime (256668719) and next prime (256668721).

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

It is not an unprimeable number, because it can be changed into a prime (256668721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 5969019 + ... + 5969061.

It is an arithmetic number, because the mean of its divisors is an integer number (1767744).

Almost surely, 2^256668720 is an apocalyptic number.

256668720 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 256668720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (565678080).

256668720 is an abundant number, since it is smaller than the sum of its proper divisors (874687440).

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

256668720 is a wasteful number, since it uses less digits than its factorization.

256668720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113 (or 107 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 42.

The square root of 256668720 is about 16020.8838707482. The cubic root of 256668720 is about 635.5128186353.

The spelling of 256668720 in words is "two hundred fifty-six million, six hundred sixty-eight thousand, seven hundred twenty".