820856823 has 4 divisors (see below), whose sum is σ = 1094475768. Its totient is φ = 547237880.

The previous prime is 820856807. The next prime is 820856831. The reversal of 820856823 is 328658028.

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 820856823 - 2⁴ = 820856807 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820856123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 136809468 + ... + 136809473.

It is an arithmetic number, because the mean of its divisors is an integer number (273618942).

Almost surely, 2^820856823 is an apocalyptic number.

820856823 is a deficient number, since it is larger than the sum of its proper divisors (273618945).

820856823 is a wasteful number, since it uses less digits than its factorization.

820856823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 273618944.

The product of its (nonzero) digits is 184320, while the sum is 42.

The square root of 820856823 is about 28650.5989989738. The cubic root of 820856823 is about 936.3160561069.

The spelling of 820856823 in words is "eight hundred twenty million, eight hundred fifty-six thousand, eight hundred twenty-three".