820781843 has 4 divisors (see below), whose sum is σ = 938036400. Its totient is φ = 703527288.

The previous prime is 820781827. The next prime is 820781891. The reversal of 820781843 is 348187028.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 820781843 - 2⁴ = 820781827 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 820781843.

It is not an unprimeable number, because it can be changed into a prime (820781813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58627268 + ... + 58627281.

It is an arithmetic number, because the mean of its divisors is an integer number (234509100).

Almost surely, 2^820781843 is an apocalyptic number.

820781843 is a deficient number, since it is larger than the sum of its proper divisors (117254557).

820781843 is a wasteful number, since it uses less digits than its factorization.

820781843 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117254556.

The product of its (nonzero) digits is 86016, while the sum is 41.

The square root of 820781843 is about 28649.2904449656. The cubic root of 820781843 is about 936.2875464190.

The spelling of 820781843 in words is "eight hundred twenty million, seven hundred eighty-one thousand, eight hundred forty-three".