861819 has 8 divisors (see below), whose sum is σ = 1313280. Its totient is φ = 492456.

The previous prime is 861803. The next prime is 861823. The reversal of 861819 is 918168.

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

It is not a de Polignac number, because 861819 - 2⁴ = 861803 is a prime.

It is a super-2 number, since 2×861819² = 1485463977522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 861819.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861829) 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, 20499 + ... + 20540.

It is an arithmetic number, because the mean of its divisors is an integer number (164160).

2⁸⁶¹⁸¹⁹ is an apocalyptic number.

861819 is a deficient number, since it is larger than the sum of its proper divisors (451461).

861819 is a wasteful number, since it uses less digits than its factorization.

861819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41049.

The product of its digits is 3456, while the sum is 33.

The square root of 861819 is about 928.3420705753. The cubic root of 861819 is about 95.1638538834.

The spelling of 861819 in words is "eight hundred sixty-one thousand, eight hundred nineteen".