256666780 has 48 divisors (see below), whose sum is σ = 557476416. Its totient is φ = 99187200.

The previous prime is 256666777. The next prime is 256666789. The reversal of 256666780 is 87666652.

It is a Smith number, since the sum of its digits (46) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 256666780.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256666789) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 110592 + ... + 112888.

It is an arithmetic number, because the mean of its divisors is an integer number (11614092).

Almost surely, 2^256666780 is an apocalyptic number.

256666780 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 256666780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (278738208).

256666780 is an abundant number, since it is smaller than the sum of its proper divisors (300809636).

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

256666780 is a wasteful number, since it uses less digits than its factorization.

256666780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2494 (or 2492 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 46.

The square root of 256666780 is about 16020.8233246609. The cubic root of 256666780 is about 635.5112174819.

The spelling of 256666780 in words is "two hundred fifty-six million, six hundred sixty-six thousand, seven hundred eighty".