855781 has 2 divisors, whose sum is σ = 855782. Its totient is φ = 855780.

The previous prime is 855739. The next prime is 855787. The reversal of 855781 is 187558.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 801025 + 54756 = 895^2 + 234^2 .

It is a cyclic number.

It is not a de Polignac number, because 855781 - 2⁹ = 855269 is a prime.

It is a super-2 number, since 2×855781² = 1464722239922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (855787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 427890 + 427891.

It is an arithmetic number, because the mean of its divisors is an integer number (427891).

2⁸⁵⁵⁷⁸¹ is an apocalyptic number.

It is an amenable number.

855781 is a deficient number, since it is larger than the sum of its proper divisors (1).

855781 is an equidigital number, since it uses as much as digits as its factorization.

855781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11200, while the sum is 34.

The square root of 855781 is about 925.0843204811. The cubic root of 855781 is about 94.9410899776.

The spelling of 855781 in words is "eight hundred fifty-five thousand, seven hundred eighty-one".