861605 has 4 divisors (see below), whose sum is σ = 1033932. Its totient is φ = 689280.

The previous prime is 861599. The next prime is 861613. The reversal of 861605 is 506168.

861605 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 474721 + 386884 = 689^2 + 622^2 .

It is not a de Polignac number, because 861605 - 2⁴ = 861589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86156 + ... + 86165.

It is an arithmetic number, because the mean of its divisors is an integer number (258483).

2⁸⁶¹⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

861605 is a deficient number, since it is larger than the sum of its proper divisors (172327).

861605 is a wasteful number, since it uses less digits than its factorization.

861605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172326.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 861605 is about 928.2268041810. The cubic root of 861605 is about 95.1559764557.

The spelling of 861605 in words is "eight hundred sixty-one thousand, six hundred five".