861823 has 2 divisors, whose sum is σ = 861824. Its totient is φ = 861822.

The previous prime is 861803. The next prime is 861829. The reversal of 861823 is 328168.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-861823 is a prime.

861823 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 861791 and 861800.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (861829) 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, 430911 + 430912.

It is an arithmetic number, because the mean of its divisors is an integer number (430912).

2⁸⁶¹⁸²³ is an apocalyptic number.

861823 is a deficient number, since it is larger than the sum of its proper divisors (1).

861823 is an equidigital number, since it uses as much as digits as its factorization.

861823 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2304, while the sum is 28.

The square root of 861823 is about 928.3442249511. The cubic root of 861823 is about 95.1640011126.

The spelling of 861823 in words is "eight hundred sixty-one thousand, eight hundred twenty-three".