861831 has 12 divisors (see below), whose sum is σ = 1285440. Its totient is φ = 555840.

The previous prime is 861829. The next prime is 861853. The reversal of 861831 is 138168.

861831 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 861831 - 2¹ = 861829 is a prime.

It is a super-2 number, since 2×861831² = 1485505345122, which contains 22 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 861795 and 861804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861871) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1266 + ... + 1823.

It is an arithmetic number, because the mean of its divisors is an integer number (107120).

2⁸⁶¹⁸³¹ is an apocalyptic number.

861831 is a deficient number, since it is larger than the sum of its proper divisors (423609).

861831 is a wasteful number, since it uses less digits than its factorization.

861831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3126 (or 3123 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 861831 is about 928.3485336876. The cubic root of 861831 is about 95.1642955697.

Adding to 861831 its reverse (138168), we get a palindrome (999999).

It can be divided in two parts, 8618 and 31, that added together give a square (8649 = 93²).

The spelling of 861831 in words is "eight hundred sixty-one thousand, eight hundred thirty-one".