21002200020 has 60 divisors (see below), whose sum is σ = 65884684404. Its totient is φ = 5600586240.

The previous prime is 21002199989. The next prime is 21002200097. The reversal of 21002200020 is 2000220012.

It can be written as a sum of positive squares in 2 ways, for example, as 4196707524 + 16805492496 = 64782^2 + 129636^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21002199975 and 21002200011.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 6480541 + ... + 6483780.

Almost surely, 2^21002200020 is an apocalyptic number.

21002200020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21002200020 is an abundant number, since it is smaller than the sum of its proper divisors (44882484384).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21002200020 is a wasteful number, since it uses less digits than its factorization.

21002200020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12964342 (or 12964331 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

Adding to 21002200020 its reverse (2000220012), we get a palindrome (23002420032).

The spelling of 21002200020 in words is "twenty-one billion, two million, two hundred thousand, twenty".