20210221002121 has 4 divisors (see below), whose sum is σ = 20213803745044. Its totient is φ = 20206638259200.

The previous prime is 20210221002077. The next prime is 20210221002133. The reversal of 20210221002121 is 12120012201202.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12255677657721 + 7954543344400 = 3500811^2 + 2820380^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20210221002121 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20210221002095 and 20210221002104.

It is not an unprimeable number, because it can be changed into a prime (20210221002151) 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, 1791363000 + ... + 1791374281.

It is an arithmetic number, because the mean of its divisors is an integer number (5053450936261).

Almost surely, 2^{20210221002121} is an apocalyptic number.

It is an amenable number.

20210221002121 is a deficient number, since it is larger than the sum of its proper divisors (3582742923).

20210221002121 is an equidigital number, since it uses as much as digits as its factorization.

20210221002121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3582742922.

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

Adding to 20210221002121 its reverse (12120012201202), we get a palindrome (32330233203323).

The spelling of 20210221002121 in words is "twenty trillion, two hundred ten billion, two hundred twenty-one million, two thousand, one hundred twenty-one".