859821 has 8 divisors (see below), whose sum is σ = 1186080. Its totient is φ = 553392.

The previous prime is 859801. The next prime is 859823. The reversal of 859821 is 128958.

It is a happy number.

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

It is not a de Polignac number, because 859821 - 2¹⁸ = 597677 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (859823) 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, 4855 + ... + 5028.

It is an arithmetic number, because the mean of its divisors is an integer number (148260).

2⁸⁵⁹⁸²¹ is an apocalyptic number.

It is an amenable number.

859821 is a deficient number, since it is larger than the sum of its proper divisors (326259).

859821 is a wasteful number, since it uses less digits than its factorization.

859821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9915.

The product of its digits is 5760, while the sum is 33.

The square root of 859821 is about 927.2653341951. The cubic root of 859821 is about 95.0902558678.

The spelling of 859821 in words is "eight hundred fifty-nine thousand, eight hundred twenty-one".