256757780 has 18 divisors (see below), whose sum is σ = 539341866. Its totient is φ = 102674448.

The previous prime is 256757747. The next prime is 256757789. The reversal of 256757780 is 87757652.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 205406224 + 51351556 = 14332^2 + 7166^2 .

It is a Smith number, since the sum of its digits (47) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256757789) 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 5 ways as a sum of consecutive naturals, for example, 69869 + ... + 73451.

It is an arithmetic number, because the mean of its divisors is an integer number (29963437).

Almost surely, 2^256757780 is an apocalyptic number.

256757780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256757780 is an abundant number, since it is smaller than the sum of its proper divisors (282584086).

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

256757780 is an frugal number, since it uses more digits than its factorization.

256757780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7175 (or 3590 counting only the distinct ones).

The product of its (nonzero) digits is 823200, while the sum is 47.

The square root of 256757780 is about 16023.6631267635. The cubic root of 256757780 is about 635.5863144455.

The spelling of 256757780 in words is "two hundred fifty-six million, seven hundred fifty-seven thousand, seven hundred eighty".