556781 has 2 divisors, whose sum is σ = 556782. Its totient is φ = 556780.

The previous prime is 556769. The next prime is 556789. The reversal of 556781 is 187655.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 434281 + 122500 = 659^2 + 350^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-556781 is a prime.

It is a super-2 number, since 2×556781² = 620010163922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (556789) 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 as a sum of consecutive naturals, namely, 278390 + 278391.

It is an arithmetic number, because the mean of its divisors is an integer number (278391).

2⁵⁵⁶⁷⁸¹ is an apocalyptic number.

It is an amenable number.

556781 is a deficient number, since it is larger than the sum of its proper divisors (1).

556781 is an equidigital number, since it uses as much as digits as its factorization.

556781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8400, while the sum is 32.

The square root of 556781 is about 746.1775928021. The cubic root of 556781 is about 82.2674688739.

The spelling of 556781 in words is "five hundred fifty-six thousand, seven hundred eighty-one".