861780 has 48 divisors (see below), whose sum is σ = 2467584. Its totient is φ = 224640.

The previous prime is 861761. The next prime is 861797. The reversal of 861780 is 87168.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

861780 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 15 ways as a sum of consecutive naturals, for example, 3045 + ... + 3315.

It is an arithmetic number, because the mean of its divisors is an integer number (51408).

2⁸⁶¹⁷⁸⁰ 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 861780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1233792).

861780 is an abundant number, since it is smaller than the sum of its proper divisors (1605804).

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

861780 is a wasteful number, since it uses less digits than its factorization.

861780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 336 (or 334 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 30.

The square root of 861780 is about 928.3210651493. The cubic root of 861780 is about 95.1624183746.

Adding to 861780 its product of nonzero digits (2688), we get a palindrome (864468).

The spelling of 861780 in words is "eight hundred sixty-one thousand, seven hundred eighty".