819864 has 48 divisors (see below), whose sum is σ = 2269800. Its totient is φ = 267264.

The previous prime is 819853. The next prime is 819899. The reversal of 819864 is 468918.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

819864 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4152 + ... + 4344.

2⁸¹⁹⁸⁶⁴ 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 819864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1134900).

819864 is an abundant number, since it is smaller than the sum of its proper divisors (1449936).

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

819864 is a wasteful number, since it uses less digits than its factorization.

819864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 264 (or 257 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 819864 is about 905.4634172621. The cubic root of 819864 is about 93.5938413656.

The spelling of 819864 in words is "eight hundred nineteen thousand, eight hundred sixty-four".