21210020202121 has 8 divisors (see below), whose sum is σ = 21420751948488. Its totient is φ = 20999302800000.

The previous prime is 21210020202071. The next prime is 21210020202169. The reversal of 21210020202121 is 12120202001212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 3153163761225 + 18056856440896 = 1775715^2 + 4249336^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21210020202121 - 2⁹ = 21210020201609 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210020202095 and 21210020202104.

It is not an unprimeable number, because it can be changed into a prime (21210020202221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 601810 + ... + 6540811.

It is an arithmetic number, because the mean of its divisors is an integer number (2677593993561).

Almost surely, 2^{21210020202121} is an apocalyptic number.

It is an amenable number.

21210020202121 is a deficient number, since it is larger than the sum of its proper divisors (210731746367).

21210020202121 is a wasteful number, since it uses less digits than its factorization.

21210020202121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7172123.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21210020202121 its reverse (12120202001212), we get a palindrome (33330222203333).

The spelling of 21210020202121 in words is "twenty-one trillion, two hundred ten billion, twenty million, two hundred two thousand, one hundred twenty-one".