256658721228 has 960 divisors, whose sum is σ = 922351288320. Its totient is φ = 60354201600.

The previous prime is 256658721217. The next prime is 256658721301. The reversal of 256658721228 is 822127856652.

256658721228 is a `hidden beast` number, since 2 + 56 + 6 + 587 + 2 + 1 + 2 + 2 + 8 = 666.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 319 ways as a sum of consecutive naturals, for example, 609640458 + ... + 609640878.

It is an arithmetic number, because the mean of its divisors is an integer number (960782592).

Almost surely, 2^256658721228 is an apocalyptic number.

256658721228 is a gapful number since it is divisible by the number (28) 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 256658721228, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (461175644160).

256658721228 is an abundant number, since it is smaller than the sum of its proper divisors (665692567092).

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

256658721228 is a wasteful number, since it uses less digits than its factorization.

256658721228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 540 (or 529 counting only the distinct ones).

The product of its digits is 6451200, while the sum is 54.

The spelling of 256658721228 in words is "two hundred fifty-six billion, six hundred fifty-eight million, seven hundred twenty-one thousand, two hundred twenty-eight".