820139 has 4 divisors (see below), whose sum is σ = 839256. Its totient is φ = 801024.

The previous prime is 820133. The next prime is 820163. The reversal of 820139 is 931028.

820139 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 820139 - 2¹² = 816043 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (820133) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9494 + ... + 9579.

It is an arithmetic number, because the mean of its divisors is an integer number (209814).

2⁸²⁰¹³⁹ is an apocalyptic number.

820139 is a deficient number, since it is larger than the sum of its proper divisors (19117).

820139 is a wasteful number, since it uses less digits than its factorization.

820139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19116.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 820139 is about 905.6152604721. The cubic root of 820139 is about 93.6043046575.

Subtracting 820139 from its reverse (931028), we obtain a square (110889 = 333²).

It can be divided in two parts, 820 and 139, that added together give a palindrome (959).

The spelling of 820139 in words is "eight hundred twenty thousand, one hundred thirty-nine".