861855 has 8 divisors (see below), whose sum is σ = 1378992. Its totient is φ = 459648.

The previous prime is 861853. The next prime is 861857. The reversal of 861855 is 558168.

It is an interprime number because it is at equal distance from previous prime (861853) and next prime (861857).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 861855 - 2¹ = 861853 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861853) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28714 + ... + 28743.

It is an arithmetic number, because the mean of its divisors is an integer number (172374).

2⁸⁶¹⁸⁵⁵ is an apocalyptic number.

861855 is a deficient number, since it is larger than the sum of its proper divisors (517137).

861855 is a wasteful number, since it uses less digits than its factorization.

861855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57465.

The product of its digits is 9600, while the sum is 33.

The square root of 861855 is about 928.3614597774. The cubic root of 861855 is about 95.1651789300.

The spelling of 861855 in words is "eight hundred sixty-one thousand, eight hundred fifty-five".