256619664 has 210 divisors, whose sum is σ = 869098950. Its totient is φ = 73156608.

The previous prime is 256619651. The next prime is 256619669. The reversal of 256619664 is 466916652.

256619664 is a `hidden beast` number, since 25 + 6 + 619 + 6 + 6 + 4 = 666.

256619664 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 228614400 + 28005264 = 15120^2 + 5292^2 .

It is not an unprimeable number, because it can be changed into a prime (256619669) by changing a digit.

It is a polite number, since it can be written in 41 ways as a sum of consecutive naturals, for example, 571312 + ... + 571760.

Almost surely, 2^256619664 is an apocalyptic number.

256619664 is a gapful number since it is divisible by the number (24) 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 256619664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (434549475).

256619664 is an abundant number, since it is smaller than the sum of its proper divisors (612479286).

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

256619664 is an equidigital number, since it uses as much as digits as its factorization.

256619664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 489 (or 461 counting only the distinct ones).

The product of its digits is 466560, while the sum is 45.

The square root of 256619664 is about 16019.3527959153. The cubic root of 256619664 is about 635.4723284355.

The spelling of 256619664 in words is "two hundred fifty-six million, six hundred nineteen thousand, six hundred sixty-four".