861000 has 128 divisors (see below), whose sum is σ = 3144960. Its totient is φ = 192000.

The previous prime is 860971. The next prime is 861001. The reversal of 861000 is 168.

861000 = 26² + 27² + ... + 137².

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a nialpdrome in base 10.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 861000.

It is not an unprimeable number, because it can be changed into a prime (861001) by changing a digit.

861000 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 20980 + ... + 21020.

It is an arithmetic number, because the mean of its divisors is an integer number (24570).

2⁸⁶¹⁰⁰⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 861000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1572480).

861000 is an abundant number, since it is smaller than the sum of its proper divisors (2283960).

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

861000 is a wasteful number, since it uses less digits than its factorization.

861000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72 (or 58 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 861000 is about 927.9008567730. The cubic root of 861000 is about 95.1336990991.

Adding to 861000 its reverse (168), we get a palindrome (861168).

The spelling of 861000 in words is "eight hundred sixty-one thousand".