861666 has 16 divisors (see below), whose sum is σ = 1856064. Its totient is φ = 265104.

The previous prime is 861659. The next prime is 861691. The reversal of 861666 is 666168.

861666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5446 + ... + 5601.

It is an arithmetic number, because the mean of its divisors is an integer number (116004).

2⁸⁶¹⁶⁶⁶ is an apocalyptic number.

861666 is an abundant number, since it is smaller than the sum of its proper divisors (994398).

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

861666 is a wasteful number, since it uses less digits than its factorization.

861666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11065.

The product of its digits is 10368, while the sum is 33.

The square root of 861666 is about 928.2596619481. The cubic root of 861666 is about 95.1582220236.

The spelling of 861666 in words is "eight hundred sixty-one thousand, six hundred sixty-six".