256781620 has 24 divisors (see below), whose sum is σ = 541986984. Its totient is φ = 102189696.

The previous prime is 256781597. The next prime is 256781621. The reversal of 256781620 is 26187652.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 17522596 + 239259024 = 4186^2 + 15468^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 256781620.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256781621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28647 + ... + 36526.

It is an arithmetic number, because the mean of its divisors is an integer number (22582791).

Almost surely, 2^256781620 is an apocalyptic number.

256781620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256781620 is an abundant number, since it is smaller than the sum of its proper divisors (285205364).

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

256781620 is a wasteful number, since it uses less digits than its factorization.

256781620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65379 (or 65377 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 37.

The square root of 256781620 is about 16024.4070093093. The cubic root of 256781620 is about 635.6059852662.

The spelling of 256781620 in words is "two hundred fifty-six million, seven hundred eighty-one thousand, six hundred twenty".