855989 has 2 divisors, whose sum is σ = 855990. Its totient is φ = 855988.

The previous prime is 855983. The next prime is 855997. The reversal of 855989 is 989558.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 828100 + 27889 = 910^2 + 167^2 .

It is a cyclic number.

It is not a de Polignac number, because 855989 - 2⁸ = 855733 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 855989.

It is not a weakly prime, because it can be changed into another prime (855983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 427994 + 427995.

It is an arithmetic number, because the mean of its divisors is an integer number (427995).

2⁸⁵⁵⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

855989 is a deficient number, since it is larger than the sum of its proper divisors (1).

855989 is an equidigital number, since it uses as much as digits as its factorization.

855989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 129600, while the sum is 44.

The square root of 855989 is about 925.1967358351. The cubic root of 855989 is about 94.9487812549.

Adding to 855989 its product of digits (129600), we get a palindrome (985589).

The spelling of 855989 in words is "eight hundred fifty-five thousand, nine hundred eighty-nine".