820200021 has 16 divisors (see below), whose sum is σ = 1109262336. Its totient is φ = 539017776.

The previous prime is 820200019. The next prime is 820200049. The reversal of 820200021 is 120002028.

It is not a de Polignac number, because 820200021 - 2¹ = 820200019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820200001) 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 15 ways as a sum of consecutive naturals, for example, 62956 + ... + 74858.

It is an arithmetic number, because the mean of its divisors is an integer number (69328896).

Almost surely, 2^820200021 is an apocalyptic number.

It is an amenable number.

820200021 is a deficient number, since it is larger than the sum of its proper divisors (289062315).

820200021 is a wasteful number, since it uses less digits than its factorization.

820200021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12232.

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 820200021 is about 28639.1344317526. The cubic root of 820200021 is about 936.0662608782.

Adding to 820200021 its reverse (120002028), we get a palindrome (940202049).

The spelling of 820200021 in words is "eight hundred twenty million, two hundred thousand, twenty-one".