2120210021 has 4 divisors (see below), whose sum is σ = 2124280044. Its totient is φ = 2116140000.

The previous prime is 2120210003. The next prime is 2120210051. The reversal of 2120210021 is 1200120212.

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 228916900 + 1891293121 = 15130^2 + 43489^2 .

It is a cyclic number.

It is not a de Polignac number, because 2120210021 - 2²⁶ = 2053101157 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 2120209984 and 2120210011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2120210051) 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, 2034230 + ... + 2035271.

It is an arithmetic number, because the mean of its divisors is an integer number (531070011).

Almost surely, 2^2120210021 is an apocalyptic number.

It is an amenable number.

2120210021 is a deficient number, since it is larger than the sum of its proper divisors (4070023).

2120210021 is an equidigital number, since it uses as much as digits as its factorization.

2120210021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4070022.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 2120210021 is about 46045.7383587233. The cubic root of 2120210021 is about 1284.6740776365.

Adding to 2120210021 its reverse (1200120212), we get a palindrome (3320330233).

The spelling of 2120210021 in words is "two billion, one hundred twenty million, two hundred ten thousand, twenty-one".