820863 has 12 divisors (see below), whose sum is σ = 1193920. Its totient is φ = 543456.

The previous prime is 820837. The next prime is 820873. The reversal of 820863 is 368028.

It is not a de Polignac number, because 820863 - 2¹³ = 812671 is a prime.

It is a Duffinian number.

820863 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820873) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1803 + ... + 2211.

2⁸²⁰⁸⁶³ is an apocalyptic number.

820863 is a deficient number, since it is larger than the sum of its proper divisors (373057).

820863 is a wasteful number, since it uses less digits than its factorization.

820863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 638 (or 635 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 820863 is about 906.0149005397. The cubic root of 820863 is about 93.6318404714.

Subtracting from 820863 its sum of digits (27), we obtain a square (820836 = 906²).

The spelling of 820863 in words is "eight hundred twenty thousand, eight hundred sixty-three".