861684 has 12 divisors (see below), whose sum is σ = 2010624. Its totient is φ = 287224.

The previous prime is 861659. The next prime is 861691. The reversal of 861684 is 486168.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 35892 + ... + 35915.

It is an arithmetic number, because the mean of its divisors is an integer number (167552).

2⁸⁶¹⁶⁸⁴ is an apocalyptic number.

It is an amenable number.

861684 is an abundant number, since it is smaller than the sum of its proper divisors (1148940).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

861684 is a wasteful number, since it uses less digits than its factorization.

861684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71814 (or 71812 counting only the distinct ones).

The product of its digits is 9216, while the sum is 33.

The square root of 861684 is about 928.2693574604. The cubic root of 861684 is about 95.1588846300.

It can be divided in two parts, 86 and 1684, that added together give a triangular number (1770 = T₅₉).

The spelling of 861684 in words is "eight hundred sixty-one thousand, six hundred eighty-four".